Anti-axl antibodies

ABSTRACT

Antibodies characterized by their variable sequences/CDRs which specifically bind to the Axl protein are described. Also disclosed are methods for the production and use of the anti-Axl antibodies.

The present disclosure relates to antibodies which specifically bind tothe Axl protein. Also disclosed are methods for the production and useof the anti-Axl antibodies.

BACKGROUND

Axl is a member of the TAM (Tyro3-Axl-Mer) receptor tyrosine kinases(RTK) that share the vitamin K—dependent ligand Gas6 (growtharrest—specific 6). TAM family RTKs regulate a diverse range of cellularresponses including cell survival, proliferation, autophagy, migration,angiogenesis, platelet aggregation, and natural killer celldifferentiation. Axl is expressed in many embryonic tissues and isthought to be involved in mesenchymal and neural development, withexpression in adult tissues largely restricted to smooth muscle cells(MGI Gene Expression Database; www.informatics.jax.org). Axl activationis linked to several signal transduction pathways, including Akt, MAPkinases, NF-κB, STAT, and others. Originally identified as atransforming gene from a patient with chronic myelogenous leukaemia, Axlhas since been associated with various high-grade cancers and correlatedwith poor prognosis.

Axl receptor overexpression has been detected in a wide range of solidtumours and myeloid leukaemia (Linger et al, Adv Cancer Res. 100: 35,2008; Linger et al, Expert Opin Ther Targets. 14:1073, 2010).

Axl expression correlates with malignant progression and is anindependent predictor of poor patient overall survival in severalmalignancies including pancreatic (Song et al, Cancer. 117:734, 2011),prostate (Paccez et al, Oncogene. 32:698, 2013), lung (Ishikawa et al.Ann Surg Oncol. 2012; Zhang et al, Nat Genet. 44:852, 2012), breast(Gjerdrum, Proc natl Acad Sci USA 107:1124, 2010), colon cancer (Yuen etal, PLoS One, 8:e54211, 2013) and acute myeloid leukaemia (AML)(Ben-Batalla et al, Blood 122:2443, 2013).

Axl signal transduction is activated by a protein ligand (Gas6) secretedby tumour associated macrophages (Loges et al, Blood. 115:2264, 2010) orautocrine mechanisms (Gjerdrum, Proc natl Acad Sci USA 107:1124, 2010),that drives receptor dimerization, autophosphorylation and downstreamsignalling, such as via PI3 kinase (PI3K)-AKT, particularly AKT andmitogen-activated protein kinase (MAPK) pathways (Korshunov, ClinicalScience. 122:361, 2012). Heterodimerization with other tyrosine kinasereceptors, e.g. epidermal growth factor receptor (EGFR), is alsoreported to occur (Linger et al, Expert Opin Ther Targets. 14:1073,2010; Meyer et al Science Signalling 6:ra66, 2013).

Aberrant activation of Axl in tumour cells is widely associated withacquired drug resistance to targeted therapeutics in vitro and in vivo(Zhang et al. Nat Genet. 44: 852, 2012; Byers et al. Clin Cancer Res.19: 279, 2013). Axl-targeting agents block tumour formation, metastasisand reverse drug resistance (e.g. to erlotinib) by reversing EMT/CSCcharacteristics in several experimental cancer models, including triplenegative breast cancer, hormone resistant prostate cancer andadenocarcinoma of the lung (Holland et al Cancer Res 70:1544, 2010;Gjerdrum, Proc natl Acad Sci USA 107:1124, 2010; Zhang et al. Nat Genet.44: 852, 2012; Paccez et al, Oncogene. 32:698, 2013).

Other applications relating to Axl and anti-Axl antibodies includeEP2267454A2 [Diagnosis and prevention of cancer cell invasion measuring. . . Axl—Max Planck]; WO2009063965 [anti Axl—Chugai Pharmaceutical];WO2011159980A1 [anti-Axl—Genentech], WO2011014457A1 [combinationtreatments Axl and VEGF antagonists—Genentech]; WO2012-175691A1 [AntiAxl 20G7-D9—INSERM], WO2012-175692A1 [Anti Axl 3E3E8—INSERM];WO2009/062690A1 [anti Axl—U3 Pharma] and WO2010/130751A1 [humanised antiAxl—U3 Pharma].

In view of the role of Axl in tumourigenesis, it is desirable toidentify further antibodies with advantageous properties, whichspecifically bind Axl. The present disclosure concerns such antibodies.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 Binding of monoclonal antibody (MAb) 1H12 to Axl⁺ triple-negativebreast cancer cell line MDA-MB-231 in flow cytometry. MAb 1H12 wasconjugated with Alexa647 (Invitrogen) and incubated with eitherMDA-MB-231 cells having knocked down Axl expression or with cellstransfected with a control shRNA. The cell staining was measured usingAccuri C6 flow cytometer (BD Biosciences). The knockdown level wasmeasured using values of geometric mean fluorescent intensity.

FIG. 2 Overlay plot of sensograms from a binding analysis showinginteractions of MAb 1H12 with recombinant human (rh) Axl, rhMer andrhTyro3. The curves after subtraction of blank surface signals areshown.

FIG. 3 Biacore analyses of ligands (MAb 1H12 and rmGas6) interactingwith a sensor chip CM5 coated with rhAxl, rmAxl and rhTyro3-Fc. Thecurves after subtraction of blank surface signals are shown.

FIG. 4 Kinetic analysis of MAb 1H12 interacting with rhAxl immobilizedon the surface of the Biacore sensor chip. Overlay plot of sensogramsfor different concentrations (1.3-666.7 nM) of MAb 1H12 is shown. Theprecise kinetic analysis was performed using BIAevaluation software andcurve fitting according to the model ‘1:1 binding with mass transfer’.The affinity constants (kinetic and steady state) as well as thecalculated half-live of antigen binding at 25° C. are shown in the insetTable.

FIG. 5 Analysis of the competition between MAb 1H12 (1st sample) andanti-Axl MAb 1H12, MAbs 1-3, rhGas6 and rmGas6 (2nd samples) usingBiacore 3000. The overlay plot of sensograms using different 2nd samplesis shown. Start points of injections of the 1st sample (1H12) and the2nd sample are indicated with arrows.

FIG. 6 Western blot analysis of anti-Axl MAb 1H12 binding to recombinanthuman (rh) Mer-Fc and Axl-Fc antigens under reducing and non-reducingconditions. Lanes: M, molecular weight markers (Magic Mark), the MWvalues in kDa are shown on the left; 1, rhAxl-Fc, non-reduced; 2,rhMer-Fc, non-reduced; 3, rhAxl-Fc, reduced; 4, rhMer-Fc, reduced. Theprotein bands corresponding to rhAxl-Fc are indicated with arrows.

FIG. 7 Western blot analysis of anti-Axl MAb 1H12 binding to the lysatesof Axl+ and Axl− cells under reducing and non-reducing conditions.Lanes: M, molecular weight markers (Magic Mark), the MW values in kDaare shown on the left; 1, lysate of Axl− LNCaP cells (prostaticadenocarcinoma), reduced; 2, lysate of Axl+ NCI-H1299 (non-small celllung carcinoma), reduced; 3, lysate of Axl+ NCl-H1299, non-reduced. Theprotein bands corresponding to Axl receptor are indicated with an arrow.

FIG. 8 Amino acid sequences of the VH and VL domains derived fromanti-Axl monoclonal antibody 1H12.

FIG. 9 Dose-dependent binding of anti-Axl mouse antibody 1H12 and itschimeric (mouse variable/human constant) counterpart to Axl-positivecells. Different concentrations of mouse (m 1H12) and chimeric (ch 1H12)antibodies were tested in flow cytometry for binding to triple-negativebreast cancer cell line MDA-MB-231. The bound mouse and chimericantibodies were detected with APC-conjugated donkey F(ab′)2 fragmentsspecific for either mouse IgG (H+L), 1:500 dilution, or human IgG (H+L),1:300 dilution, respectively (both from Jackson ImmunoResearch). Thecell staining was measured using Accuri C6 flow cytometer (BDBiosciences). MFI, geometric mean fluorescence intensity.

FIG. 10 Kinetic analysis of chimeric MAb ch1H12 interacting with rhAxlimmobilized on the surface of the Biacore sensor chip. Overlay plot ofsensograms for different concentrations (1.3-666.7 nM) of MAb ch1H12 isshown. The precise kinetic analysis was performed using BIAevaluationsoftware and curve fitting according to 1:1 Langmuir binding model. Theaffinity constants (kinetic and steady state) as well as the calculatedhalf-live of antigen binding at 25° C. are shown in the inset Table.

FIG. 11 Biacore analysis of the murine antibody 1H12 interacting with asensor chip coated with human-Axl-Fc, cyno-Axl-Fc and rhesus-Axl-Fc.

FIG. 12 Tumour cell killing using antibody-Saporin conjugates.Unconjugated Saporin and an isotype control antibody (human IgG1)coupled to Saporin (control SAP) were used as negative controls.Effective concentrations leading to 50% cell killing (EC₅₀, pM) areshown in the inset Table.

FIG. 13 Western blot analysis illustrating agonistic activity of 1H12antibody cross-linked with the secondary anti-mouse antibodies.Phosphorylation of Akt on Serm was used as surrogate readout for Axlactivity. Lanes: 1, molecular weight markers; 2, positive control(lysate of LNCaP cells from prostatic adenocarcinoma); 3, lysate of HeLacells after starvation; 4, HeLa cells after starvation treated withcross-linked 1H12. Immunoblots of total cell lysates were probed withanti-phospho-Akt (Ser⁴⁷³).

FIG. 14 Western blot analysis illustrating dose-dependent agonisticactivity of 1H12 antibody cross-linked with the secondary anti-mouseantibodies. Phosphorylation of Akt on Ser⁴⁷³ was used as surrogatereadout for Axl activity. Lanes: 1, molecular weight markers; 2,positive control (lysate of LNCaP cells from prostatic adenocarcinoma);3, lysate of HeLa cells after starvation; 4-7, HeLa cells afterstarvation treated with different doses of cross-linked 1H12 (0.2, 0.6,2.0 and 6.0 μg/ml, respectively). Immunoblots of total cell lysates wereprobed with anti-phospho-Akt (Ser⁴⁷³).

FIG. 15 Western blot analysis illustrating agonistic activity of 1H12antibody alone. Phosphorylation of Akt on Ser⁴⁷³ was used as surrogatereadout for Axl activity. Lanes: 1, molecular weight markers; 2,positive control (lysate of LNCaP cells from prostatic adenocarcinoma);3, lysate of HeLa cells after starvation; 4, lysate of HeLa cells afterstarvation additionally treated with Axl-Fc; 5, HeLa cells afterstarvation treated with cross-linked 1H12; 6, HeLa cells afterstarvation treated with cross-linked 1H12 lone. Immunoblots of totalcell lysates were probed with anti-phospho-Akt (Ser⁴⁷³).

FIG. 16 Analysis of the competition between MAb 1H12 as a 1st sample andeither anti-Axl MAB154 or rmGas6 as 2nd samples using Biacore 3000. Theoverlay plot of sensograms using different 2nd samples is shown. Startpoints of injections of the 1st sample (1H12) and the 2nd sample areindicated with arrows.

FIG. 17 Comparative IHC staining of Axl+ and Axl− (A) cells using MAb1H12, commercial antibody polyclonal AF154, and monoclonal MAB154. Wildtype (wt) and Axl-knocked down MDA-MB-231 cells were used as Axl+ andAxl− cells, respectively. (B) Comparative Western blot analysis of Axl+and Axl− cell lysates (wt and Axl-knocked-down MDA-MB-231 cells)developed using either MAb 1H12 or polyclonal AF154 and monoclonalMAB154. As a loading control, GAPDH detection is shown on every blot.

DISCLOSURE OF THE INVENTION

The following sequences are disclosed herein (see ‘SEQUENCES’ sectionbelow for full sequence):

SEQ ID NO.1→1H12 VH encoding nucleotide sequenceSEQ ID NO.2→1H12 VL encoding nucleotide sequenceSEQ ID NO.3→1H12 VH encoding amino acid sequenceSEQ ID NO.4→1H12 VL encoding amino acid sequenceSEQ ID NO.5→1H12 VH CDR1 encoding amino acid sequenceSEQ ID NO.6→1H12 VH CDR2 encoding amino acid sequenceSEQ ID NO.7→1H12 VH CDR3 encoding amino acid sequenceSEQ ID NO.8→1H12 VL CDR1 encoding amino acid sequenceSEQ ID NO.9→1H12 VL CDR2 encoding amino acid sequenceSEQ ID NO.10→1H12 VL CDR3 encoding amino acid sequenceSEQ ID NO.11→1H12 VH FR1 encoding amino acid sequenceSEQ ID NO.12→1H12 VH FR2 encoding amino acid sequenceSEQ ID NO.13→1H12 VH FR3 encoding amino acid sequenceSEQ ID NO.14→1H12 VH FR4 encoding amino acid sequenceSEQ ID NO.15→1H12 VL FR1 encoding amino acid sequenceSEQ ID NO.16→1H12 VL FR2 encoding amino acid sequenceSEQ ID NO.17→1H12 VL FR3 encoding amino acid sequenceSEQ ID NO.18→1H12 VL FR4 encoding amino acid sequenceSEQ ID NO.19→Human Axl encoding amino acid sequenceSEQ ID NO.20→Murine Axl encoding amino acid sequenceSEQ ID NO.21→Human Tyro3 encoding amino acid sequenceSEQ ID NO.22→Human Mer encoding amino acid sequence

In one aspect, the present invention provides an isolated antibody whichbinds Axl and which comprises the 1H12 VH domain (SEQ ID NO: 3) and/orthe 1H12 VL domain (SEQ ID NO: 4). Preferably the bound Axl is humanAxl.

Generally, a VH domain is paired with a VL domain to provide an antibodyantigen binding site, although as discussed further below a VH domainalone may be used to bind antigen. In one preferred embodiment, the 1H12VH domain (SEQ ID NO: 3) is paired with the 1H12 VL domain (SEQ ID NO:4), so that an antibody antigen binding site is formed comprising boththe 1H12 VH and VL domains. In other embodiments, the 1H12 VH is pairedwith a VL domain other than the 1H12 VL. Light-chain promiscuity is wellestablished in the art.

One or more CDR's may be taken from the 1H12 VH or VL domain andincorporated into a suitable framework. This is discussed further below.1H12 VH CDR's 1, 2 and 3 are shown in SEQ ID Nos 5, 6 and 7,respectively. 1H12 VL CDR's 1, 2 and 3 are shown in SEQ ID Nos 8, 9, and10, respectively.

In one aspect of the invention, there is provided an antibody that bindsAxl and which comprises:

-   -   an antibody VH domain selected from the group consisting of the        1H12 VH domain (SEQ ID NO.3) and a VH domain comprising a VH        CDR3 with the amino acid sequence of SEQ ID NO.7 and optionally        one or more VH CDR's with an amino acid sequence selected from        SEQ ID NO.6 and SEQ ID NO.5; and/or    -   an antibody VL domain selected from the group consisting of the        1H12 VL domain (SEQ ID NO. 4) and a VL domain comprising one or        more VL CDR's with an amino acid sequence selected from SEQ ID        NO.8, SEQ ID NO.9 and SEQ ID NO.10.

For example, the antibody may comprise an antibody VH domain comprisingthe VH CDR's with the amino acid sequences of SEQ ID NO.5, SEQ ID NO.6and SEQ ID NO.7. The antibody may further comprise an antibody VL domaincomprising the VL CDR's with the amino acid sequences of SEQ ID NO.8,SEQ ID NO.9 and SEQ ID NO.10.

In some embodiments the antibody comprises: (i) an antibody VH domaincomprising the VH CDR's with the amino acid sequences of SEQ ID NO.5,SEQ ID NO.6 and SEQ ID NO.7, and (ii) an antibody VL domain comprisingthe VL CDR's with the amino acid sequences of SEQ ID NO.8, SEQ ID NO.9and SEQ ID NO.10.

The antibody may comprise the 1H12 VH domain (SEQ ID NO. 3) and,optionally, further comprise the 1H12 VL domain (SEQ ID NO. 4)

Preferably, the antibody competes for binding to human Axl with an Axlbinding domain of an antibody comprising the 1H12 VH domain (SEQ ID NO.3) and the 1H12 VL domain (SEQ ID NO. 4).

According to a further aspect of the invention, there are providedvariants of the VH and VL domains of which the sequences are set outherein and which can be employed in antibodies for Axl and can beobtained by means of methods of sequence alteration or mutation andscreening. Such methods are also provided by the present invention.

Variable domain amino acid sequence variants of any of the VH and VLdomains whose sequences are specifically disclosed herein may beemployed in accordance with the present invention, as discussed.Particular variants may include one or more amino acid sequencealterations (addition, deletion, substitution and/or insertion of anamino acid residue), maybe less than about 20 alterations, less thanabout 15 alterations, less than about 10 alterations or less than about5 alterations, 4, 3, 2 or 1. Alterations may be made in one or moreframework regions and/or one or more CDR's.

An antibody according to the invention may be one which competes forbinding to antigen with any antibody which both binds the antigen andcomprises an antibody VH and/or VL domain disclosed herein, or VH CDR3disclosed herein, or variant of any of these. That is, in someembodiments the antibody according to the invention is an antibody whichbinds the same epitope or an overlapping epitope as an antibody whichcomprises an antibody VH and/or VL domain disclosed herein, or VH CDR3disclosed herein, or variant of any of these. Competition betweenantibody may be assayed easily in vitro, for example using ELISA, usingbinding analysis in a Biacore 3000 machine (see, for example, Example 15& FIG. 16), and/or by tagging a specific reporter molecule to oneantibody which can be detected in the presence of other untaggedantibody(s), to enable identification of antibodies which bind the sameepitope or an overlapping epitope.

Accordingly, the present invention comprises a variant of anyspecifically disclosed herein, wherein the variant comprises one or moreamino acid sequence alterations in one or more framework regions and/orone or more CDRs. For example, the variant antibody may comprise no morethan 4 sequence alterations in any one CDR, such as no more than 3, nomore than 2, no more than 1 sequence alterations, or no sequencealterations in any one CDR (such as CDR3 of the VH domain). The variantantibody may compete for binding to Axl (for example, human Axl) with anAxl binding domain of an antibody comprising the 1H12 VH domain (SEQ IDNO. 3) and the 1H12 VL domain (SEQ ID NO. 4).

Thus a further aspect of the present invention provides an antibodycomprising a human antibody antigen-binding site which competes with1H12 for binding to human Axl.

Various methods are available in the art for obtaining antibodiesagainst Axl and which may compete with 1H12 for binding to Axl.

In a further aspect, the present invention provides a method ofobtaining one or more antibodies able to bind the antigen, the methodincluding bringing into contact a library of antibodies according to theinvention and said antigen, and selecting one or more antibody membersof the library able to bind said antigen.

The library may be displayed on the surface of bacteriophage particles,each particle containing nucleic acid encoding the antibody VH variabledomain displayed on its surface, and optionally also a displayed VLdomain if present.

Following selection of antibodies able to bind the antigen and displayedon bacteriophage particles, nucleic acid may be taken from abacteriophage particle displaying a said selected antibody. Such nucleicacid may be used in subsequent production of an antibody or an antibodyVH variable domain (optionally an antibody VL variable domain) byexpression from nucleic acid with the sequence of nucleic acid takenfrom a bacteriophage particle displaying a said selected antibody.

An antibody VH variable domain with the amino acid sequence of anantibody VH variable domain of a said selected antibody may be providedin isolated form, as may an antibody comprising such a VH domain.

Ability to bind Axl may be further tested, also ability to compete with1H12 for binding to Axl.

An antibody according to the present invention may bind Axl with theaffinity of 1H12.

An antibody of the invention may bind to murine, rat, monkey, non-humanprimate and/or human Axl. Preferably, the antibody binds to human andmonkey Axl. In some embodiments the antibody specifically binds primateAxl. For example, the antibody may specifically bind human and monkeyAxl. In one embodiment the antibody specifically binds only human Axl.

The antibody may be a chimeric, humanised, or CDR-grafted anti-Axlantibody. For example, the antibody may be a chimeric human/mouseantibody.

Binding affinity and neutralisation potency of different antibodies canbe compared under appropriate conditions.

In addition to antibody sequences, an antibody according to the presentinvention may comprise other amino acids, e.g. forming a peptide orpolypeptide, such as a folded domain, or to impart to the moleculeanother functional characteristic in addition to ability to bindantigen.

Antibodies of the invention may carry a detectable label, or may beconjugated to a toxin (such as a cytotoxin), enzyme, or an organicmoiety (e.g. via a peptidyl bond or linker).

Those skilled in the art are aware of numerous approaches to chemicallyconjugating molecules to proteins. In one embodiment of the presentinvention, the antibody can be conjugated to a detectable, fluorescentlabel, e.g. fluorescein isothiocyanate (FITC), or to a reporter enzymesuch as horseradish peroxidase (HRP)

In a preferred embodiment, the antibody is conjugated to a cytotoxicdrug with a formation of the antibody-drug conjugate (ADC). When theantibody is for pharmaceutical use, the bond linking the antibody anddrug is preferably stable in circulation (for example, bloodcirculation) but labile once the conjugate is sequesteredintracellularly. Thus, the antibody conjugated as an immunoconjugate maybe used in a method of treatment of, for example, cancer.

In further aspects, the invention provides an isolated nucleic acidwhich comprises a sequence encoding an antibody, VH domain and/or VLdomain according to the present invention, and methods of preparing anantibody, a VH domain and/or a VL domain of the invention, whichcomprise expressing said nucleic acid under conditions to bring aboutproduction of said antibody, VH domain and/or VL domain, and recoveringit.

Antibodies according to the invention may be used in a method oftreatment or diagnosis of the human or animal body, such as a method oftreatment (which may include prophylactic treatment) of a disease ordisorder in a human patient which comprises administering to saidpatient an effective amount of an antibody of the invention, or aconjugate, or drug-conjugate thereof. Conditions treatable in accordancewith the present invention include those discussed elsewhere herein.

Antibodies according to the invention may be used in a method ofimaging, for example, to determine the presence or location of cells towhich the antibody binds.

In a further aspect, the present invention provides a diagnostic kitcomprising an antibody according to the invention and one or morereagents to determine binding of the antibody to the antigen.

A further aspect of the present invention provides nucleic acid,generally isolated, encoding an antibody VH variable domain (SEQ ID NO:3) and/or VL variable domain (SEQ ID NO: 4) disclosed herein. In someembodiments the VH encoding nucleic acid has the sequence set out in SEQID NO: 1. In some embodiments the VL encoding nucleic acid has thesequence set out in SEQ ID NO: 2.

Another aspect of the present invention provides nucleic acid, generallyisolated, encoding a VH CDR or VL CDR sequence disclosed herein,especially a VH CDR selected from SEQ ID NOs 5, 6, and 7 or a VL CDRselected from SEQ ID NOs 8, 9, or 10, most preferably 1H12 CDR3 (SEQ IDNO: 7).

A further aspect provides a host cell transformed with nucleic acid ofthe invention.

A yet further aspect provides a method of production of an antibody VHvariable domain, the method including causing expression from encodingnucleic acid. Such a method may comprise culturing host cells underconditions for production of said antibody VH variable domain.

Analogous methods for production of VL variable domains and antibodiescomprising a VH and/or VL domain are provided as further aspects of thepresent invention.

A method of production may comprise a step of isolation and/orpurification of the product.

A method of production may comprise formulating the product into acomposition including at least one additional component, such as apharmaceutically acceptable excipient.

These and other aspects of the invention are described in further detailbelow.

Antibody Properties High Affinity for Axl

The 1H12 antibody described herein binds to human Axl with highaffinity. As described in Example 4, the 1H12 antibody was determined tohave a K_(D) of 4.98×10⁻¹¹ M. This is the lowest K_(D) yet described foran anti-Axl antibody.

Unexpectedly, the chimeric MAb ch1H12 (see Example 11 & FIG. 10) hashigher affinity still, with a K_(D)=1.10×10⁻¹¹ M; this figure is4.5-fold lower than the parental murine antibody, possibly due to abetter orientation of the VH and VL domains when mounted on a humanconstant domain scaffold.

Accordingly, the antibodies described herein bind Axl with highaffinity; preferably human Axl is bound with high affinity. In someembodiments, an antibody binds to Axl (or human Axl) with a K_(D) nogreater than 10⁻⁶ M, such as no greater than 5×10⁻⁷ M, no greater than10⁻⁷ M, no greater than 5×10⁻⁸ M, no greater than 10⁻⁸ M, no greaterthan 5×10⁻⁹ M, no greater than 10⁻⁹ M, no greater than 5×10⁻¹⁰ M, nogreater than 10⁻¹⁹ M, no greater than 5×10⁻¹¹ M, no greater than1.5×10⁻¹¹ M, no greater than 10⁻¹¹ M, no greater than 5×10⁻¹² M, nogreater than 10⁻¹² M, no greater than 5×10⁻¹³ M, no greater than 10⁻¹³M, no greater than 5×10⁻¹⁴ M, no greater than 10⁻¹⁴ M, no greater than5×10⁻¹⁵ M, or no greater than 10⁻¹⁵ M.

In some embodiments, an antibody binds to Axl (or human Axl) with aK_(D) from 10⁻⁸ M to 10⁻¹⁰ M, from 10⁻¹⁰ M to 10⁻¹², from 10⁻¹² M to10⁻¹⁴, or from 10⁻¹⁴ M to 10⁻¹⁶.

The K_(D) may be determined and calculated as set out in Example 4.

The 1H12 antibody described herein is characterized by having a veryslow dissociation rate (k_(off)). Specifically, in Example 4 the 1H12antibody was determined to have very slow dissociation rate(k_(off)=1.07×10⁻⁵ s⁻¹).

Unexpectedly, the chimeric MAb ch1H12 (see Example 11 & FIG. 10) haslower disassociation rate still, with a k_(off)=2.99×10⁻⁶ s⁻¹), whichresulted in 64.4 hr half-life of the ch1H12/Axl complex.

Accordingly, the antibodies described herein preferably bind human Axlwith a slow disassociation rate. In some embodiments, an antibody bindsto Axl (or human Axl) with a k_(off) no greater than 10⁻³ s⁻¹, such asno greater than 5×10⁻⁴ s⁻¹, no greater than 10⁻⁴ s⁻¹, no greater than5×10⁻⁵ s⁻¹, no greater than 2×10⁻⁵ s⁻¹, no greater than 10⁻⁵ s⁻¹, nogreater than 3×10⁻⁶ s⁻¹, no greater than 5×10⁻⁶ s⁻¹, no greater than10⁻⁶ s⁻¹, no greater than 5×10⁻⁷ s⁻¹, no greater than 10⁻⁷ s⁻¹, nogreater than 5×10⁻⁸ s⁻¹, or no greater than 10⁻⁸ s⁻¹.

Specific Binding

Generally, the terms ‘specific’ and ‘specifically binds’ may be used torefer to the situation in which an antibody will not show anysignificant binding to molecules other than its specific bindingpartner(s). For example, an antibody which ‘specifically binds’ humanAxl would not show any significant binding for murine Axl.

The term is also applicable where e.g. an antibody is specific for aparticular epitope which is carried by a number of antigens, in whichcase an antibody which ‘specifically binds’ an epitope will be able tobind to all of the various antigens which carry the recognised epitope.

Typically, specificity may be determined by means of a binding assaysuch as ELISA employing a panel of antigens.

The 1H12 antibody described herein binds to human Axl with highspecificity. This is demonstrated in the examples, where it is shownthat:

-   -   (1) In Example 2, 1H12 shows no significant binding to        recombinant antigens derived from hMer and hTyro3, the other        members of the human TAM receptor tyrosine kinase family.    -   (2) In Example 3, 1H12 binds strongly to human Axl, but shows no        binding to murine Axl (this is in contrast to murine Axl ligand,        murine Gas 6, which binds strongly to both murine and human Axl,        as well as (more weakly) binding human Tyro3);    -   (3) In Example 9, 1H12 shows either no or very little binding to        the overwhelming majority of the tested tissue samples.

Accordingly, the antibodies described herein preferably specificallybind primate Axl. In some embodiments the antibodies described hereinspecifically bind human and monkey Axl. In one embodiment the antibodiesspecifically bind only human Axl.

In some embodiments of the present invention, the antibodies describedherein show no significant binding to human Tyro3 and/or human Mer. Insome embodiments the antibodies described herein show no significantbinding to murine Axl. In some embodiments the antibodies describedherein show no significant binding to any of human Tyro3, human Mer, ormurine Axl.

Whether an antibody shows “no significant binding” to an antigen can bereadily determined by the skilled person using, for example, thetechniques described in Examples 2 and 3. In some embodiments, anantibody is deemed to show “no significant binding” to a particularantigen if it binds the antigen with a K_(D) greater than 10⁻³ M, suchas greater than 10⁻² M, greater than 10⁻¹ M, or greater than 1 M. TheK_(D) may be determined and calculated as set out in Example 4.

In one aspect, the antibodies of the invention bind the same epitope asthe 1H12 antibody, or an epitope which overlaps with the epitope boundby the 1H12 antibody. Competition between different antibodies may beassayed easily in vitro, for example using ELISA and/or by tagging aspecific reporter molecule to one binding member which can be detectedin the presence of other untagged antibody(ies), to enableidentification of antibodies which bind the same epitope or anoverlapping epitope.

Antibody Internalisation

The 1H12 antibody described herein demonstrates good cellinternalisation upon binding its target, Axl. Internalisation is alsoobserved when the antibody is conjugated to a cytotoxin, such as Saporin(see Example 13 & FIG. 12).

Accordingly, the antibodies of the invention, or conjugates thereof, arepreferably internalised following binding to Axl present on a cellsurface.

Utility in Axl Detection

The unexpectedly good binding properties of the antibodies describedherein make them particularly effective in applications involving thedetection of Axl. For example, comparative tests have shown that the1H12 antibody gives a notably stronger signal than the commercialanti-Axl antibodies to AF154 and MAB154 in both immunohistochemistry andwestern blotting applications (see Example 16 and FIG. 17); competitionanalysis indicates that 1H12 and MAB154 bind the same or overlappingepitope (see FIG. 16). This stronger signal and increased sensitivity ofAxl detection provides a significant advantage in detection andanalytical assays.

Agonism of Axl Signalling

The 1H12 antibody described herein can induce Axl signalling on bindingto Axl. This is demonstrated in Example 14, along with FIGS. 13-15,where 1H12 binding is seen to induce strong Axl signalling in adose-dependent manner as determined by measuring phosphorylation of theAxl-effector Akt on Ser⁴⁷³.

Accordingly, in one aspect the antibodies described herein agonise Axlsignalling; that is, the antibodies described herein are preferably Axlagonists.

In a further aspect, the present invention provides an antibody whichbinds the same epitope or an overlapping epitope as an antibody whichcomprises an antibody VH and/or VL domain disclosed herein, or VH CDR3disclosed herein, or variant of any of these, wherein the antibody is anAxl agonist. Binding of the same or an overlapping epitope can bereadily determine in vitro by completion studies, as described herein.

In some embodiments Axl signalling is at least 10% greater in thepresence of the antibody of the invention than in the presence of anon-Axl binding control antibody; for example, at least 10% greater, atleast 20% greater, at least 30% greater, at least 40% greater, at least50% greater, at least 60% greater, at least 70% greater, at least 80%greater, at least 90% greater, at least 100% greater, at least 200%greater, at least 500% greater or at least 1000% greater, in thepresence of the antibody of the invention than in the presence of anon-Axl binding control antibody. The level of Axl signalling may beassessed by measuring phosphorylation of the Axl-effector Akt on Ser⁴⁷³,as described herein in Example 14.

Down-Regulation of Axl Expression and/or Activity

In some embodiments, an anti-Axl antibody induces down-regulation of Axlreceptor expression on a cell surface (e.g. a tumour cell surface).

In some embodiments, cell surface Axl expression is reduced to less than80% of Axl cell surface expression in the absence of Axl antibodytreatment. In some embodiments, cell surface expression is reduced toless than 70%, less than 60%, less than 50% or less than 40% of Axl cellsurface expression in the absence of Axl antibody treatment.

In some embodiments, total Axl expression in a cell (e.g., a tumourcell) is reduced to less than 80% of total Axl expression in the absenceof Axl antibody treatment. In some embodiments, total Axl expression isreduced to less than 70%, less than 60%, less than 50% or less than 40%of total Axl expression in the absence of Axl antibody treatment. Insome embodiments, down-regulation of Axl expression occurs rapidly andlasts for at least 24 hours.

In some embodiments, an anti-Axl antibody inhibits constitutive Axlactivity.

In some embodiments, an anti-Axl antibody inhibits Axl activity.

In some embodiments, an anti-Axl antibody promotes cell death, forexample by apoptosis e.g., a tumour cell, such as a A549 tumour cell;this may be measured by, for example BrdU incorporation assay, MTT,[³H]-thymidine incorporation (e.g., TopCount assay (PerkinElmer)), cellviability assays (e.g., CellTiter-Glo (Promega)), DNA fragmentationassays, caspase activation assays, tryptan blue exclusion, chromatinmorphology assays and the like.

In some embodiments, an anti-Axl antibody inhibits Axl downstreamsignalling. In some embodiments, an anti-Axl antibody inhibits Gas6dependent cell proliferation.

In some embodiments, an anti-Axl antibody inhibits inflammatory cytokineexpression from tumour-associated macrophages.

In some embodiments, an anti-Axl antibody inhibits tumour growth and/ormetastasis by modulating tumour stromal function.

DEFINITIONS Antibody

This term describes an immunoglobulin whether natural or partly orwholly synthetically produced. The term also covers any polypeptide orprotein comprising an antibody antigen-binding domain. Antibodyfragments which comprise an antibody antigen-binding domain includewhole antibodies (for example an IgG antibody comprising VH, CH1, CH2,CH3, VL, and CL domains in the canonical arrangement), or fragments ofwhole antibodies which retain their binding activity for a targetantigen. Such fragments include Fv (fragment variable), Fab (fragmentantibody binding) and F(ab′)₂ fragments, as well as single-chain Fvantibodies (scFv), dsFv, minibodies, diabodies, single-chain diabodies,tandem scFv, TandAb, bi-body, tri-body, kappa(lambda) body, BiTE,DVD-Ig, SIP, SMIP, or DART. Furthermore, the antibodies and fragmentsthereof may be humanised antibodies, for example as described inEP239400A. For example: monoclonal and polyclonal antibodies,recombinant antibodies, proteolytic and recombinant fragments ofantibodies (Fab, Fv, scFv, diabodies), single-domain antibodies (VHH,sdAb, nanobodies, IgNAR, VNAR), and proteins unrelated to antibodies,which have been engineered to have antibody-like specific binding(antibody mimetics), such as the following, but not limited to:

Name Based on: Adnectins/ 10th type III domain of human Monobodiesfibronectin (10Fn3), 10 kDa Affibodies Protein A, Z domain, 6 kDa)Affilins Human γ-crystallin/human ubiquitin (10-20 kDa) Affitins Sac7d(from Sulfolobus acidocaldarius), 7 kDa Anticalins Lipocalins, 20 kDaAvimers Domains of various membrane receptors, 9-18 kDa DARPins Ankyrinrepeat motif, 14 kDa Evibody Cytotoxic T-Lymphocyte Antigen 4 (CTLA-4),15 kDa Fynomers Fyn, SH3 domain, 7 kDa Kunitz domain Various proteaseinhibitors, 6 kDa peptides

An antibody may comprise all or apportion of an antibody heavy chainconstant region and/or an antibody light chain constant region.

It is possible to take monoclonal and other antibodies and usetechniques of recombinant DNA technology to produce engineeredantibodies or chimeric molecules, which retain the specificity of theoriginal antibody. Such techniques may involve ligation of DNA fragmentsencoding the immunoglobulin variable regions, or the complementaritydetermining regions (CDRs), of an antibody with genes coding for theimmunoglobulin constant regions, or the constant regions plus frameworkregions, of a different immunoglobulin. See, for instance, EP-A-184187,GB 2188638A or EP-A-239400. A hybridoma or other cell producing anantibody may be subject to genetic mutation or other changes, which mayor may not alter the binding specificity of antibodies produced.

As antibodies can be modified in a number of ways, the term “antibodymolecule” should be construed as covering any polypeptide or othermolecule having an antibody-derived antigen-binding domain with therequired specificity. Thus, this term covers antibody fragments andderivatives, including any polypeptide comprising an immunoglobulinbinding domain, whether natural or wholly or partially synthetic.Chimeric molecules comprising an immunoglobulin binding domain, orequivalent, fused to another polypeptide are therefore included. Cloningand expression of chimeric antibodies are described in EP-A-0120694 andEP-A-0125023.

It has been shown that fragments of a whole antibody can perform thefunction of binding antigens. Examples of binding fragments are (i) theFab fragment consisting of VL, VH, CL and CH1 domains; (ii) the Fdfragment consisting of the VH and CH1 domains; (iii) the Fv fragmentconsisting of the VL and VH domains of a single antibody; (iv) the dAbfragment (Ward, E. S. et al., Nature 341, 544-546 (1989)) which consistsof a VH domain; (v) isolated CDR regions; (vi) F(ab′)2 fragments, abivalent fragment comprising two linked Fab fragments; (vii) singlechain Fv molecules (scFv), wherein a VH domain and a VL domain arelinked by a peptide linker which allows the two domains to associate toform an antigen binding site (Bird et al, Science, 242, 423-426, 1988;Huston et al, PNAS USA, 85, 5879-5883, 1988); (viii) bispecific singlechain Fv dimers (PCT/US92/09965) and (ix) “diabodies”, multivalent ormultispecific fragments constructed by gene fusion (WO94/13804; P.Holliger et al, Proc. Natl. Acad. Sci. USA 90, 6444-6448, 1993). Fv,scFv or diabody molecules may be stabilised by the incorporation ofdisulphide bridges linking the VH and VL domains (Y. Reiter et al,Nature Biotech, 14, 1239-1245, 1996). Minibodies comprising a scFvjoined to a CH3 domain may also be made (S. Hu et al, Cancer Res., 56,3055-3061, 1996).

The antibody may be bispecific or multispecific. Where bispecificantibodies are to be used, these may be conventional bispecificantibodies, which can be manufactured in a variety of ways (Holliger, P.and Winter G. Current Opinion Biotechnol. 4, 446-449 (1993)), e.g.prepared chemically or from hybrid hybridomas, or may be any of thebispecific antibody fragments mentioned above. Diabodies and scFv can beconstructed without an Fc region, using only variable domains,potentially reducing the side effects, such as those due to the antibodyeffector functions, or human-anti-mouse antibody (HAMA) response in caseof using antibodies of murine origin.

Bispecific diabodies, as opposed to bispecific whole antibodies, mayalso be particularly useful because they can be readily constructed andexpressed in bacteria (e.g. Escherichia coli). Diabodies (and many otherpolypeptides such as antibody fragments) of appropriate bindingspecificities can be readily selected using phage display (WO94/13804)from the antibody libraries. If one arm of the diabody is to be keptconstant, for instance, with a specificity directed against Axl, then alibrary can be made where the other arm is varied and an antibody ofappropriate specificity selected. Bispecific whole antibodies may bemade by “knobs-into-holes” engineering (J. B. B. Ridgeway et al, ProteinEng., 9, 616-621, 1996).

Antigen Binding Domain

This describes the part of an antibody molecule which comprises the areawhich recognizes and specifically binds to and is complementary part orall of an antigen. Where an antigen is large, an antibody may only bindto a particular part of the antigen, which part is termed an epitope. Anantigen binding domain may be provided by one or more antibody variabledomains (e.g. a so-called Fd antibody fragment consisting of a VHdomain). Preferably, an antigen binding domain comprises an antibodylight chain variable region (VL) and an antibody heavy chain variableregion (VH).

Specific Proteins Human Axl

As used herein, ‘human Axl’ refers to the Axl member of the human TAMfamily of receptor tyrosine kinases. In some embodiments, the human Axlpolypeptide corresponds to Genbank accession no. AAH32229, version no.AAH32229.1 GI:21619004, record update date: Mar. 6, 2012 01:18 PM (SEQID NO.19). In one embodiment, the nucleic acid encoding the human Axlpolypeptide corresponds to Genbank accession no. M76125, version no.M76125.1 GI:292869, record update date: Jun. 23, 2010 08:53 AM.

Murine Axl

As used herein, ‘murine Axl’ refers to the Axl member of the murine TAMfamily of receptor tyrosine kinases. In some embodiments, the murine Axlpolypeptide corresponds to Genbank accession no. AAH46618, version no.AAH46618.1 GI:55777082, record update date: Mar. 6, 2012 01:36 PM (SEQID NO.20). In one embodiment, the nucleic acid encoding the murine Axlpolypeptide corresponds to Genbank accession no. NM_009465, version no.NM_009465.4 GI:300794836, record update date: Mar. 12, 2014 03:52 PM.

Human Tyro3

As used herein, ‘human Tyro3’ refers to the Tyro3 member of the humanTAM family of receptor tyrosine kinases. In some embodiments, the humanTyro3 polypeptide corresponds to Genbank accession no. 006418, versionno. 006418.1 GI:1717829, record update date: Apr. 22, 2014 12:07 PM (SEQID NO.21). In one embodiment, the nucleic acid encoding the human Tyro3polypeptide corresponds to Genbank accession no. BC051756, version no.BC051756.1 GI:30704372, record update date: Mar. 6, 2012 01:43 PM.

Human Mer

As used herein, ‘human Mer’ refers to the Mer member of the human TAMfamily of receptor tyrosine kinases (official name=MERTK, UniprotID=012866). In some embodiments, the human Mer polypeptide correspondsto Genbank accession no. AA114918, version no. AAI14918.1 GI:109732052,record update date: Mar. 6, 2012 04:21 PM (SEQ ID NO.22). In oneembodiment, the nucleic acid encoding the human Mer polypeptidecorresponds to Genbank accession no. NM_006343, version no. NM_006343.2GI:66932917, record update date: Mar. 16, 2014 08:52 PM.

BSA

As used herein, ‘BSA’ refers to Bovine Serum Albumin. In someembodiments BSA corresponds to Genbank accession no. CAA76847, versionno. CAA76847.1 GI:3336842, record update date: Jan. 7, 2011 02:30 PM.

Comprise

This is generally used in the sense of “include”, that is to saypermitting the presence of one or more features or components.

Isolated

This refers to the state in which antibodies of the invention, ornucleic acid encoding such antibody, will generally be in accordancewith the present invention. Antibody and nucleic acid will be free orsubstantially free of material with which they are naturally associatedsuch as other polypeptides or nucleic acids with which they are found intheir natural environment, or the environment in which they are prepared(e.g. cell culture) when such preparation is by recombinant DNAtechnology practiced in vitro or in vivo. Antibodies and nucleic acidmay be formulated with diluents or adjuvants and still for practicalpurposes be isolated—for example the antibody will normally be mixedwith gelatin or other carriers if used to coat microtitre plates for usein immunoassays, or will be mixed with pharmaceutically acceptablecarriers or diluents when used in diagnosis or therapy. Antibodies maybe glycosylated, either naturally or by systems of heterologouseukaryotic cells (e.g. CHO or NS0 (ECACC 85110503) cells), or they maybe (for example, if produced by expression in a prokaryotic cell)non-glycosylated.

Substantially as Set Out

By “substantially as set out” it is meant that the relevant CDR or VH orVL domain of the invention will be either identical or highly similar tothe specified regions of which the sequence is set out herein. By“highly similar” it is contemplated that from 1 to 5, preferably from 1to 4 such as 1 to 3 or 1 or 2, or 3 or 4, amino acid substitutions maybe made in the CDR and/or VH or VL domain.

Frameworks Supporting CDRs

The structure for carrying a CDR of the invention will generally be ofan antibody heavy or light chain sequence or substantial portion thereofin which the CDR is located at a location corresponding to the CDR ofnaturally occurring VH and VL antibody variable domains encoded byrearranged immunoglobulin genes. The structures and locations ofimmunoglobulin variable domains may be determined by reference to(Kabat, E. A. et al, Sequences of Proteins of Immunological Interest.4th Edition. US Department of Health and Human Services. 1987, andupdates thereof, now available on the Internet(http://immuno.bme.nwu.edu or find “Kabat” using any search engine).

Variable domains employed in the invention may be obtained from anygerm-line or rearranged mouse or human variable domain, or may be asynthetic variable domain based on consensus sequences of known mouse orhuman variable domains. A CDR sequence of the invention (e.g. CDR3) maybe introduced into a repertoire of variable domains lacking a CDR (e.g.CDR3), using recombinant DNA technology.

For example, Marks et al (Bio/Technology, 1992, 10:779-783) describemethods of producing repertoires of antibody variable domains in whichconsensus primers directed at or adjacent to the 5′-end of the variabledomain area are used in conjunction with consensus primers to the thirdframework region of human VH genes to provide a repertoire of VHvariable domains lacking a CDR3. Marks et al. further describe how thisrepertoire may be combined with a CDR3 of a particular antibody. Usinganalogous techniques, the CDR3-derived sequences of the presentinvention may be shuffled with repertoires of VH or VL domains lacking aCDR3, and the shuffled complete VH or VL domains combined with a cognateVL or VH domain to provide antibodies of the invention. The repertoiremay then be displayed in a suitable host system such as the phagedisplay system of WO92/01047 so that suitable antibodies may beselected. A repertoire may consist of from anything from 10⁴ individualantibody upwards, for example from 10⁶ to 10⁸ or 10¹⁰ antibodies.

Analogous shuffling or combinatorial techniques are also disclosed byStemmer (Nature, 1994, 370:389-391), who describes the technique of DNAshuffling in relation to a β-lactamase gene but observes that theapproach may be used for the generation of antibodies.

A further alternative is to generate novel VH or VL regions carrying aCDR-derived sequences of the invention using random mutagenesis of oneor more selected VH and/or VL genes to generate mutations within theentire variable domain. Such a technique is described by Gram et al(1992, Proc. Natl. Acad. Sci., USA, 89:3576-3580), who used error-pronePCR.

Another method which may be used is to direct mutagenesis to CDR regionsof VH or VL genes. Such techniques are disclosed by Barbas et al. (1994,Proc. Natl. Acad. Sci., USA, 91:3809-3813) and Schier et al. (1996, J.Mol. Biol. 263:551-567).

All the above-described techniques are known as such in the art and inthemselves do not form part of the present invention. The skilled personwill be able to use such techniques to provide antibodies of theinvention using routine methodology in the art.

Epitope-Specific Antibodies

A further aspect of the invention provides a method for obtaining anantibody specific for an Axl epitope, the method comprising providing byway of addition, deletion, substitution or insertion of one or moreamino acids in the amino acid sequence of a VH domain set out herein aVH domain which is an amino acid sequence variant of the VH domain,optionally combining the VH domain thus provided with one or more VLdomains, and testing the VH domain or VH/VL combination or combinationsfor to identify a antibody or an antibody antigen binding domainspecific for Axl. Said VL domain may have an amino acid sequence, whichis substantially as set out herein.

An analogous method may be employed in which one or more sequencevariants of a VL domain disclosed herein are combined with one or moreVH domains.

A further aspect of the invention provides a method of preparing anantibody specific for Axl, which method comprises:

-   -   (a) providing a starting repertoire of nucleic acids encoding a        VH domain which either include a CDR3 to be replaced or lack a        CDR3 encoding region;    -   (b) combining said repertoire with a donor nucleic acid encoding        an amino acid sequence substantially as set out herein for a VH        CDR3 such that said donor nucleic acid is inserted into the CDR3        region in the repertoire, so as to provide a product repertoire        of nucleic acids encoding a VH domain;    -   (c) expressing the nucleic acids of said product repertoire;    -   (d) selecting an antibody specific for Axl; and    -   (e) recovering said antibody or nucleic acid encoding it.

Again, an analogous method may be employed in which a VL CDR3 of theinvention is combined with a repertoire of nucleic acids encoding a VLdomain which either include a CDR3 to be replaced or lack a CDR3encoding region.

Similarly, one or more, or all three CDRs may be grafted into arepertoire of VH or VL domains which are then screened for an antibodyor antibodies specific for Axl.

A substantial portion of an immunoglobulin variable domain will compriseat least the three CDR regions, together with their interveningframework regions. Preferably, the portion will also include at leastabout 50% of either or both of the first and fourth framework regions,the 50% being the C-terminal 50% of the first framework region and theN-terminal 50% of the fourth framework region. Additional residues atthe N-terminal or C-terminal end of the substantial part of the variabledomain may be those not normally associated with naturally occurringvariable domain regions. For example, construction of antibodies of thepresent invention made by recombinant DNA techniques may result in theintroduction of N- or C-terminal residues encoded by linkers introducedto facilitate cloning or other manipulation steps. Other manipulationsteps include the introduction of linkers to join variable domains ofthe invention to further protein sequences including immunoglobulinheavy chains, other variable domains (for example in the production ofdiabodies) or protein labels as discussed in more details below.

Although in a preferred aspect of the invention antibodies comprising apair of VH and VL domains are preferred, single binding domains based oneither VH or VL domain sequences form further aspects of the invention.It is known that single immunoglobulin domains, especially VH domains,are capable of binding target antigens in a specific manner.

In the case of either single binding domains, these domains may be usedto screen for complementary domains capable of forming a two-domainantibody able to bind Axl.

This may be achieved by phage display screening methods using theso-called hierarchical dual combinatorial approach as disclosed inWO92/01047 in which an individual colony containing either an H or Lchain clone is used to infect a complete library of clones encoding theother chain (L or H) and the resulting two-chain antibody is selected inaccordance with phage display techniques such as those described in thatreference. This technique is also disclosed in Marks et al., ibid.

Antibodies of the present invention may further comprise antibodyconstant regions or parts thereof. For example, an antibody of thepresent invention may comprise a CL, CH1, CH2, and/or a CH3 domain (orany combination thereof). A VL domain may be attached at its C-terminalend to antibody light chain constant domains including human Cκ or Cλchains, preferably Cκ chains. Similarly, an antibody based on a VHdomain may be attached at its C-terminal end to all or part of animmunoglobulin heavy chain derived from any antibody isotype, e.g. IgG,IgA, IgE and IgM and any of the isotype sub-classes. Fc regions such asΔnab and Δnac as disclosed in WO99/58572 may be employed.

Chimeric, Humanised and CDR-Grafted Antibodies

As used herein “chimeric” antibodies or “humanised” antibodies or“CDR-grafted” include any combination of the herein described anti-Axlantibodies, or any CDR derived therefrom combined with one or moreproteins or peptides derived from a non-murine, preferably, humanantibody.

Chimeric or humanised antibodies include those wherein the CDR's arederived from one or more of the herein described anti-Axl antibodies andat least a portion, or the remainder of the antibody is derived from oneor more human antibodies. Thus, the human part of the antibody mayinclude the frameworks, CL (e.g. Cκ or Cλ), CH domains (e.g., CH1, CH2,CH3), hinge regions which are substantially non-immunogenic in humans.

The regions of the antibody that are derived from human antibodies neednot have 100% identity with human antibodies. In a preferred embodiment,as few of the mouse amino acid residues as possible are retained inorder for the immunogenicity to be negligible, but the mouse residuesmay be retained as necessary to support the antigen binding site formedby the CDR's while simultaneously maximizing the humanization of theantibody. Such changes or variations optionally and preferably retain orreduce the immunogenicity in humans or other species relative tonon-modified antibodies.

It should be noted that a humanised antibody can be produced by anon-human animal or prokaryotic or eukaryotic cell that is capable ofexpressing functionally rearranged human immunoglobulin (e.g., heavychain and/or light chain) genes. Further, when the antibody is a singlechain antibody, it can comprise a linker peptide that is not found innative human antibodies. For example, an scFv can comprise a linkerpeptide, such as two to about twenty glycine or other amino acidresidues (preferably glycine and serine residues (e.g., Gly₄Ser orGly₂Ser repeats)), which connects the variable region of the heavy chainand the variable region of the light chain. Such linker peptides areconsidered to be non-immunogenic in humans. In some embodiments thelinker is of at least 12 amino acids in length.

Antibody humanisation can be performed by, for example, synthesizing acombinatorial library comprising all six CDRs of a non-human targetmonoclonal antibody fused in frame to a pool of individual humanframeworks. A human framework library that contains genes representativeof all known heavy and light chain human germline sequences can beutilized. The resulting combinatorial libraries can then be screened forbinding to antigens of interest. This approach can allow for theselection of the most favourable combinations of fully human frameworksin terms of maintaining the binding activity to the parental antibody.Humanised antibodies can then be further optimized by a variety oftechniques.

For full-length antibody molecules, the immunoglobulin genes can beobtained from genomic DNA or mRNA of hybridoma cell lines. The antibodyheavy and light chains are cloned in a mammalian vector system. Assemblyis confirmed by sequencing using methods known in the art. The antibodyconstruct can be expressed in other human or mammalian host cell lines.The construct can then be validated by transient transfection assays andWestern blot analysis of the expressed antibody of interest. Stable celllines with the highest productivity can be isolated and screened usingrapid assay methods.

Human genes which encode the constant (C) regions of the humanizedantibodies, fragments and regions can be derived from a human fetalliver library by known methods. Human C region genes can be derived fromany human cell including those which express and produce humanimmunoglobulins. The human CH region can be derived from any of theknown classes or isotypes of human heavy chains, including γ, μ, α, δ,ε, and subclasses thereof, such as G1, G2, G3 and G4. Since the heavychain isotype is responsible for the various effector functions of anantibody, the choice of CH domain will be guided by the desired effectorfunctions, such as complement fixation, or activity inantibody-dependent cellular cytotoxicity (ADCC). Preferably, the CHdomain are derived from the gamma 1 (IgG1).

The human CL region can be derived from either human L chain isotype,kappa or lambda, preferably kappa.

Genes encoding human immunoglobulin C regions are obtained from humancells by standard cloning techniques (Sambrook, et al. MolecularCloning: A Laboratory Manual, 2nd Edition, Cold Spring Harbor Press,Cold Spring Harbor, N.Y. (1989) and Ausubel et al., eds. CurrentProtocols in Molecular Biology (1987-1993)). Human C region genes arereadily available from known clones containing genes representing thetwo types of light chains, the five classes of heavy chains andsubclasses thereof.

Chimeric antibody fragments, such as Fab and F(ab′)₂, can be prepared bydesigning a chimeric heavy chain gene which is appropriately truncated.For example, a chimeric gene encoding a heavy chain portion of anF(ab′)₂ fragment would include DNA sequences encoding the CH1 domain andhinge region of the heavy chain, followed by a translational stop codonto yield the truncated molecule.

Methods for engineering or humanizing non-human or human antibodies canbe used and are well known in the art. Generally, a humanized orengineered antibody has one or more amino acid residues from a sourcewhich is non-human, e.g., but not limited to mouse, rat, rabbit,non-human primate or other mammal. These human amino acid residues areoften referred to as “import” residues, which are typically taken froman “import” variable, constant or other domain of a known humansequence. Known human Ig sequences are disclosed, e.g.,www.ncbi.nlm.nih.gov/entrez/query.fcgi; www.atcc.org/phage/hdb.html;www.sciquest.com/; www.abcam.com/;www.antibodyresource.com/onlinecomp.html;www.public.iastate.edu/.about.pedro/research_tools.html;www.mgen.uni-heidelberg.de/SD/IT/IT.html;www.whfreeman.com/immunology/CH05/kuby05.htm;www.library.thinkquest.org/12429/Immune/Antibody.html;www.hhmi.org/grants/lectures/1996/vlab/;www.path.cam.ac.uk/.about.mrc7/mikeimages.html;www.antibodyresource.com/; mcb.harvard.edu/BioLinks/Immunology.html.www.immunologylink.com/; pathbox.wustl.edu/.about.hcenter/index.html;www.biotech.ufl.edu/.about.hcl/; www.pebio.com/pa/340913/340913.html;www.nal.usda.gov/awic/pubs/antibody/;www.m.ehime-u.ac.jp/.about.yasuhito/Elisa.html;www.biodesign.com/table.asp; www.icnet.uk/axp/facs/davies/links.html;www.biotech.ufl.edu/.about.fccl/protocol.html;www.isac-net.org/sites_geo.html;aximt1.imt.uni-marburg.de/.about.rek/AEPStart.html;baserv.uci.kun.nl/.about.jraats/links1.html;www.recab.uni-hd.de/immuno.bme.nwvu.edu/;www.mrc-cpe.cam.ac.uk/imt-doc/public/INTRO.html;www.ibt.unam.mx/vir/V_mice.html; imgt.cnusc.fr:8104/;www.biochem.ucl.ac.uk/.about.martin/abs/index.html;antibody.bath.ac.uk/; abgen.cvm.tamu.edu/lab/wwwabgen.html;www.unizh.ch/.about.honegger/AHOseminar/Slide01.html;www.cryst.bbk.ac.uk/.aboutubcg07s/;www.nimr.mrc.ac.uk/CC/ccaewg/ccaewg.htm;www.path.cam.ac.uk/.about.mrc7/humanisation/TAHHP.html;www.ibt.unam.mx/vir/structure/stat_aim.html;www.biosci.missouri.edu/smithgp/index.html;www.cryst.bioc.cam.ac.uk/.about.fmolina/Web-pages/Pept/spottech.html;www.jerini.de/fr_products.htm; www.patents.ibm.con/ibm.html. Kabat etal. Sequences of Proteins of Immunological Interest, U.S. Dept. Health(1983), each entirely incorporated herein by reference.

Such imported sequences can be used to reduce immunogenicity or reduce,enhance or modify binding, affinity, on-rate, off-rate, avidity,specificity, half-life, or any other suitable characteristic, as knownin the art. Generally, part or all of the non-human or human CDRsequences are maintained while the non-human sequences of the variableand constant regions are replaced with human or other amino acids.

Antibodies can also optionally be humanized with retention of highaffinity for the antigen and other favorable biological properties. Toachieve this goal, humanized antibodies can be optionally prepared by aprocess of analysis of the parental sequences and various conceptualhumanized products using three-dimensional models of the parental andhumanized sequences. Three-dimensional immunoglobulin models arecommonly available and are familiar to those skilled in the art.Computer programs are available which illustrate and display probablethree-dimensional conformational structures of selected candidateimmunoglobulin sequences. Inspection of these displays permits analysisof the likely role of the residues in the functioning of the candidateimmunoglobulin sequence, i.e., the analysis of residues that influencethe ability of the candidate immunoglobulin to bind its antigen. In thisway, FR residues can be selected and combined from the consensus andimport sequences so that the desired antibody characteristic, such asincreased affinity for the target antigen(s), is achieved.

In general, the CDR residues are directly and most substantiallyinvolved in influencing antigen binding. Humanization or engineering theantibody can be performed using any known method, such as but notlimited to those described in Winter et al., Nature 321:522 (1986);Riechmann et al., Nature 332:323 (1988); Verhoeyen et al., Science239:1534 (1988)), Sims et al., J. Immunol. 151: 2296 (1993); Chothia andLesk, J. Mol. Biol. 196:901 (1987), Carter et al., Proc. Natl. Acad.Sci. U.S.A. 89:4285 (1992); Presta et al., J. Immunol. 151:2623 (1993),U.S. Pat. Nos. 5,723,323, 5,976,862, 5,824,514, 5,817,483, 5,814,476,5,763,192, 5,723,323, 5,766,886, 5,714,352, 6,204,023, 6,180,370,5,693,762, 5,530,101, 5,585,089, 5,225,539; 4,816,567, PCT/: US98/16280,US96/18978, US91/09630, US91/05939, US94/01234, GB89/01334, GB91/01134,GB92/01755; WO90/14443, WO90/14424, WO90/14430, EP 229246.

The human constant region of the humanized antibody can be of any classor isotype (IgG, IgA, IgM, IgE, IgD, etc.) and can comprise a kappa orlambda light chain. In one embodiment, the human constant regioncomprises an IgG heavy chain or defined fragment, for example, at leastone of the IgG subclasses, IgG1, IgG2, IgG3 or IgG4.

Labelled Antibodies

Antibodies of the invention may be labelled with a detectable orfunctional label. Detectable labels include radiolabels such as [¹³¹I]or [⁹⁹Tc], which may be attached to antibodies of the invention usingconventional chemistry known in the art of radioimmunoconjugates. Labelsalso include enzyme labels such as horseradish peroxidase. Labelsfurther include chemical moieties, such as biotin, which may be detectedvia binding to a specific cognate detectable moiety, e.g. labelledavidin or streptavidin. Preferably, the labels include fluorescentlabels such as FITC.

Organic Moiety

The modified antibodies and antigen-binding fragments can comprise oneor more organic moieties that are covalently bonded, directly orindirectly, to the antibody. Each organic moiety that is bonded to anantibody or antigen-binding fragment described herein can independentlybe a hydrophilic polymeric group, a fatty acid group or a fatty acidester group. As used herein, the term “fatty acid” encompassesmono-carboxylic acids and di-carboxylic acids. A “hydrophilic polymericgroup,” as the term is used herein, refers to an organic polymer that ismore soluble in water than in octane. For example, poly-lysine is moresoluble in water than in octane. Thus, an antibody modified by thecovalent attachment of poly-lysine is encompassed by the presentdisclosure. Hydrophilic polymers suitable for modifying antibodiesdescribed herein can be linear or branched and include, for example,poly-alkane glycols, e.g., polyethylene glycol (PEG),monomethoxy-polyethylene glycol (mPEG), PPG and the like, carbohydrates(e.g., dextran, cellulose, oligosaccharides, polysaccharides and thelike), polymers of hydrophilic amino acids (e.g., poly-lysine,poly-arginine, poly-aspartate and the like), poly-alkane oxides (e.g.,polyethylene oxide, polypropylene oxide and the like) and polyvinylpyrolidone. Preferably, the hydrophilic polymer that modifies theantibody described herein has a molecular weight of about 800 to about150,000 Daltons as a separate molecular entity. For example PEG5000 andPEG20,000, wherein the subscript is the average molecular weight of thepolymer in Daltons, can be used. The hydrophilic polymeric group can besubstituted with one to about six alkyl, fatty acid or fatty acid estergroups. Hydrophilic polymers that are substituted with a fatty acid orfatty acid ester group can be prepared by employing suitable methods.For example, a polymer comprising an amine group can be coupled to acarboxylate of the fatty acid or fatty acid ester, and an activatedcarboxylate (e.g., activated with N,N-carbonyl di-imidazole) on a fattyacid or fatty acid ester can be coupled to a hydroxyl group on apolymer.

Fatty acids and fatty acid esters suitable for modifying antibodiesdescribed herein can be saturated or can contain one or more units ofunsaturation. Fatty acids that are suitable for modifying antibodiesdescribed herein include, for example, n-dodecanoate (C12, laurate),n-tetradecanoate (C14, myristate), n-octadecanoate (C18, stearate),n-eicosanoate (C20, arachidate), n-docosanoate (C22, behenate),n-triacontanoate (C30), n-tetracontanoate (C40), cis-δ9-octadecanoate(018, oleate), all cis-δ5,8,11,14-eicosatetraenoate (C20, arachidonate),octanedioic acid, tetradecanedioic acid, octadecanedioic acid,docosanedioic acid, and the like. Suitable fatty acid esters includemono-esters of dicarboxylic acids that comprise a linear or branchedlower alkyl group. The lower alkyl group can comprise from one to abouttwelve, preferably one to about six, carbon atoms.

The modified human antibodies and antigen-binding fragments can beprepared using suitable methods, such as by reaction with one or moremodifying agents. A “modifying agent” as the term is used herein, refersto a suitable organic group (e.g., hydrophilic polymer, a fatty acid, afatty acid ester) that comprises an activating group. An “activatinggroup” is a chemical moiety or functional group that can, underappropriate conditions, react with a second chemical group therebyforming a covalent bond between the modifying agent and the secondchemical group. For example, amine-reactive activating groups includeelectrophilic groups such as tosylate, mesylate, halo (chloro, bromo,fluoro, iodo), N-hydroxysuccinimidyl esters (NHS), and the like.Activating groups that can react with thiols include, for example,maleimide, iodoacetyl, acrylolyl, pyridyl disulfides,5-thiol-2-nitrobenzoic acid thiol (TNB-thiol), and the like. An aldehydefunctional group can be coupled to amine- or hydrazide-containingmolecules, and an azide group can react with a trivalent phosphorousgroup to form phosphoramidate or phosphorimide linkages. Suitablemethods to introduce activating groups into molecules are known in theart (see for example, Hernanson, G. T., Bioconjugate Techniques,Academic Press: San Diego, Calif. (1996)). An activating group can bebonded directly to the organic group (e.g., hydrophilic polymer, fattyacid, fatty acid ester), or through a linker moiety, for example adivalent C1-C12 group wherein one or more carbon atoms can be replacedby a heteroatom such as oxygen, nitrogen or sulfur. Suitable linkermoieties include, for example, tetra-ethylene glycol, —(CH₂)₃—,—NH—(CH₂)₆—NH—, —(CH₂)₂—NH— and —CH₂—O—CH₂—CH₂—O—CH₂—CH₂—O—CH—NH—.Modifying agents that comprise a linker moiety can be produced, forexample, by reacting a mono-Boc-alkyldiamine (e.g.,mono-Boc-ethylenediamine, mono-Boc-diaminohexane) with a fatty acid inthe presence of 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) toform an amide bond between the free amine and the fatty acidcarboxylate. The Boc protecting group can be removed from the product bytreatment with trifluoroacetic acid (TFA) to expose a primary amine thatcan be coupled to another carboxylate as described, or can be reactedwith maleic anhydride and the resulting product cyclized to produce anactivated maleimido derivative of the fatty acid. (See, for example,Thompson, et al., WO 92/16221).

The modified antibodies can be produced by reacting a human antibody orantigen-binding fragment with a modifying agent. For example, theorganic moieties can be bonded to the antibody in a non-site specificmanner by employing an amine-reactive modifying agent, for example, anNHS ester of PEG. Modified human antibodies or antigen-binding fragmentscan also be prepared by reducing disulfide bonds (e.g., intra-chaindisulfide bonds) of an antibody or antigen-binding fragment. The reducedantibody or antigen-binding fragment can then be reacted with athiol-reactive modifying agent to produce the modified antibodydescribed herein. Modified human antibodies and antigen-bindingfragments comprising an organic moiety that is bonded to specific sitesof an antibody described herein can be prepared using suitable methods,such as reverse proteolysis (Fisch et al., Bioconjugate Chem., 3:147-153(1992); Werlen et al., Bioconjugate Chem., 5:411-417 (1994); Kumaran etal., Protein Sci. 6(10):2233-2241 (1997); Itoh et al., Bioorg. Chem.,24(1): 59-68 (1996); Capellas et al., Biotechnol. Bioeng., 56(4):456-463(1997)), and the methods described in Hermanson, G. T., BioconjugateTechniques, Academic Press: San Diego, Calif. (1996).

Immunoconjugates

The invention also provides immunoconjugates comprising an anti-Axlantibody herein conjugated to one or more cytotoxic agents, such aschemotherapeutic agents or drugs, growth inhibitory agents, toxins(e.g., protein toxins, enzymatically active toxins of bacterial, fungal,plant, or animal origin, or fragments thereof), or radioactive isotopes.

In one embodiment, an immunoconjugate is an antibody-drug conjugate(ADC) in which an antibody is conjugated to one or more drugs, includingbut not limited to a maytansinoid (see U.S. Pat. Nos. 5,208,020,5,416,064 and European Patent EP 0 425 235 B1); an auristatin such asmonomethylauristatin drug moieties DE and DF (MMAE and MMAF) (see U.S.Pat. Nos. 5,635,483 and 5,780,588, and 7,498,298); a dolastatin; acalicheamicin or derivative thereof (see U.S. Pat. Nos. 5,712,374,5,714,586, 5,739,116, 5,767,285, 5,770,701, 5,770,710, 5,773,001, and5,877,296; Hinman et al., Cancer Res. 53:3336-3342 (1993); and Lode etal., Cancer Res. 58:2925-2928 (1998)); an anthracycline such asdaunomycin or doxorubicin (see Kratz et al., Current Med. Chern.13:477-523 (2006); Jeffrey et al., Bioorganic & Med. Chern. Letters16:358-362 (2006); Torgov et al., Bioconj. Chern. 16:717-721 (2005);Nagy et al., Proc. Natl. Acad. Sci. USA 97:829-834 (2000); Dubowchik etal., Bioorg. & Med. Chern. Letters 12:1529-1532 (2002); King et al., J.Med. Chern. 45:4336-4343 (2002); and U.S. Pat. No. 6,630,579);methotrexate; vindesine; a taxane such as docetaxel, paclitaxel,larotaxel, tesetaxel, and ortataxel; a trichothecene; and CC1065.

In another embodiment, an immunoconjugate comprises an antibody asdescribed herein conjugated to an enzymatically active toxin or fragmentthereof, including but not limited to diphtheria toxin A chain,nonbinding active fragments of diphtheria toxin, exotoxin A chain (fromPseudomonas aeruginosa), ricin A chain, abrin A chain, modeccin A chain,alpha-sarcin, Aleurites fordii proteins, dianthin proteins, Phytolacaamericana proteins (P API, P APII, and PAP-S), momordica charantiainhibitor, curcin, crotin, sapaonaria officinalis inhibitor, gelonin,mitogellin, restrictocin, phenomycin, enomycin, and the tricothecenes.

In another embodiment, an immunoconjugate comprises an antibody asdescribed herein conjugated to a radioactive atom to form aradioimmunoconjugate. A variety of radioactive isotopes are availablefor the production of radioimmunoconjugates. Examples include [²¹¹At],[¹³¹I], [¹²⁵I], [⁹⁰Y], [¹⁸⁶Re], [¹⁸⁸Re], [¹⁵³Sm], [²¹²Bi], [³²P:],[²¹²Pb] and radioactive isotopes of Lu. When the radioimmunoconjugate isused for detection, it may comprise a radioactive atom for scintigraphicstudies, for example [⁹⁹Tc] or [¹²³I], or a spin label for nuclearmagnetic resonance (NMR) imaging (also known as magnetic resonanceimaging, MRI), such as iodine-123 again, iodine-131, indium-111,fluorine-19, carbon-13, nitrogen-15, oxygen-17, gadolinium, manganese oriron.

Conjugates of an antibody and cytotoxic agent may be made using avariety of bifunctional protein coupling agents such asN-succinimidyl-3-(2-pyridyldithio) propionate (SPDP),succinimidyl-4-(N-maleimidomethyl) cyclohexane-1-carboxylate (SMCC),iminothiolane (IT), bifunctional derivatives of imidoesters (such asdimethyl adipimidate HCl), active esters (such as disuccinimidylsuberate), aldehydes (such as glutaraldehyde), bis-azido compounds (suchas bis (p-azidobenzoyl) hexanediamine), bis-diazonium derivatives (suchas bis-(p-diazoniumbenzoyl)-ethylenediamine), diisocyanates (such astoluene 2,6-diisocyanate), and bis-active fluorine compounds (such as1,5-difluoro-2,4-dinitrobenzene). For example, a ricin immunotoxin canbe prepared as described in Vitetta et al., Science 238:1098 (1987).Carbon-14-labeled 1-isothiocyanatobenzyl-3-methyldiethylenetriaminepentaacetic acid (MXDTPA) is an exemplary chelating agent forconjugation of radionucleotide to the antibody. See WO94/11026. Thelinker may be a “cleavable linker” facilitating release of a cytotoxicdrug in the cell. For example, an acid-labile linker,peptidase-sensitive linker, photo-labile linker, dimethyl linker ordisulfide-containing linker (Chari et al., Cancer Res. 52: 127-131(1992); U.S. Pat. No. 5,208,020) may be used.

The immunoconjugates or ADCs herein expressly contemplate, but are notlimited to such conjugates prepared with cross-linker reagentsincluding, but not limited to, BMPS, EMCS, GMBS, HBVS, LC-SMCC, MBS,MPBH, SBAP, SIA, SIAB, SMCC, SMPB, SMPH, sulfo-EMCS, sulfo-GMBS,sulfo-KMUS, sulfo-MBS, sulfo-SIAB, sulfo-SMCC, and sulfo-SMPB, and SVSB(succinimidyl-(4-vinylsulfone)benzoate) which are commercially available(e.g., from Pierce Biotechnology, Inc., Rockford, Ill., U.S.A).

Glycosylation Variants

In certain embodiments, an antibody provided herein is altered toincrease or decrease the extent to which the antibody is glycosylated.Addition or deletion of glycosylation sites to an antibody may beconveniently accomplished by altering the amino acid sequence such thatone or more glycosylation sites is created or removed.

Where the antibody comprises an Fc region, the carbohydrate attachedthereto may be altered. Native antibodies produced by mammalian cellstypically comprise a branched, biantennary oligosaccharide that isgenerally attached by an N-linkage to Asn297 of the CH2 domain of the Fcregion. See, e.g., Wright et al. TIBTECH 15:26-32 (1997). Theoligosaccharide may include various carbohydrates, e.g., mannose,N-acetyl glucosamine (GlcNAc), galactose, and sialic acid, as well as afucose attached to a GlcNAc in the “stem” of the biantennaryoligosaccharide structure. In some embodiments, modifications of theoligosaccharide in an antibody of the invention may be made in order tocreate antibody variants with certain improved properties.

In one embodiment, antibody variants are provided having a carbohydratestructure that lacks fucose attached (directly or indirectly) to an Fcregion. For example, the amount of fucose in such antibody may be from1% to 80%, from 1% to 65%, from 5% to 65% or from 20% to 40%. The amountof fucose is determined by calculating the average amount of fucosewithin the sugar chain at Asn297, relative to the sum of allglycostructures attached to Asn297 (e.g., complex, hybrid and highmannose structures) as measured by MALDI-TOF mass spectrometry, asdescribed in WO 2008/077546, for example. Asn297 refers to theasparagine residue located at about position 297 in the Fc region (Eunumbering of Fc region residues); however, Asn297 may also be locatedabout ±3 amino acids upstream or downstream of position 297, i.e.,between positions 294 and 300, due to minor sequence variations inantibodies. Such fucosylation variants may have improved ADCC function.See, e.g., US Patent Publication Nos. US 2003/0157108 (Presta, L.); US2004/0093621 (Kyowa Haklw Kogyo Co., Ltd). Examples of publicationsrelated to “defucosylated” or “fucose-deficient” antibody variantsinclude: US2003/01571; WO2000/61739; WO2001/29246; US2003/0115614;US2002/0164328; US2004/0093621; US2004/0132140; US2004/0110704;US2004/0110282; US2004/0109865; WO2003/085119; WO2003/084570;WO2005/035586; WO2005/035778; WO2005/053742; WO2002/031140; Okazaki etal. J. Mol. Biol. 336:1239-1249 (2004); Yamane-Ohnuki et al. Biotech.Bioeng. 87: 614 (2004).

Examples of cell lines capable of producing defucosylated antibodiesinclude Lecl3 CHO cells deficient in protein fucosylation (Ripka et al.Arch. Biochem. Biophys. 249:533-545 (1986); US Pat Appl No US2003/0157108 A1, Presta, L; and WO 2004/056312 A1, Adams et al.,especially at Example 11), and knockout cell lines, such asalpha-1,6-fucosyltransferase gene, FUT8, knockout CHO cells (see, e.g.,Yamane-Ohnuki et al. Biotech. Bioeng. 87: 614 (2004); Kanda, Y. et al.,Biotechnol. Bioeng., 94(4):680-688 (2006); and WO2003/085107).

Antibodies variants are further provided with bisected oligosaccharides,e.g., in which a biantennary oligosaccharide attached to the Fc regionof the antibody is bisected by GlcNAc. Such antibody variants may havereduced fucosylation and/or improved ADCC function. Examples of suchantibody variants are described, e.g., in WO 2003/011878 (Jean-Mairet etal.); U.S. Pat. No. 6,602,684 (Umana et al.); and US2005/0123546 (Umanaet al.). Antibody variants with at least one galactose residue in theoligosaccharide attached to the Fe region are also provided. Suchantibody variants may have improved CDC function. Such antibody variantsare described, e.g., in WO 1997/30087 (Patel et al.); WO 1998/58964(Raju, S.); and WO 1999/22764 (Raju, S.).

Fc Region Variants

In certain embodiments, one or more amino acid modifications may beintroduced into the Fc region of an antibody provided herein, therebygenerating an Fc region variant. The Fc region variant may comprise ahuman Fc region sequence (e.g., a human IgG1, IgG2, IgG3 or IgG4 Fcregion) comprising an amino acid modification (e.g. a substitution) atone or more amino acid positions.

In certain embodiments, the invention contemplates an antibody variantthat possesses some but not all effector functions, which make it adesirable candidate for applications in which the half-life of theantibody in vivo is important yet certain effector functions (such ascomplement fixation and ADCC) are unnecessary or deleterious. In vitroand/or in vivo cytotoxicity assays can be conducted to confirm thereduction/depletion of CDC and/or ADCC activities. For example, Fcreceptor (FcR) binding assays can be conducted to ensure that theantibody lacks Fcγ binding (hence likely lacking ADCC activity), butretains FcRn binding ability. The primary cells for mediating ADCC, NKcells, express FcγRIII only, whereas monocytes express FcγRI, FcγRII andFcγRIII. FcR expression on hematopoietic cells is summarized in Table 3on page 464 of Ravetch and Kinet, Annu. Rev. Immunol. 9:457-492 (1991).Non-limiting examples of in vitro assays to assess ADCC activity of amolecule of interest is described in U.S. Pat. No. 5,500,362 (see, e.g.Hellstrom, I. et al. Proc. Nat'l Acad. Sci. USA 83:7059-7063 (1986)) andHellstrom, I et al., Proc. Nat'l Acad. Sci. USA 82:1499-1502 (1985);U.S. Pat. No. 5,821,337 (see Bruggemann, M. et al., J. Exp. Med.166:1351-1361 (1987)). Alternatively, non-radioactive assay methods maybe employed (see, for example, ACTI™ non-radioactive cytotoxicity assayfor flow cytometry (CellTechnology, Inc. Mountain View, Calif.; andCytoTox 96® non-radioactive cytotoxicity assay (Promega, Madison, Wis.).Useful effector cells for such assays include peripheral bloodmononuclear cells (PBMC) and Natural Killer (NK) cells. Alternatively,or additionally, ADCC activity of the molecule of interest may beassessed in vivo, e.g., in an animal model such as that disclosed inClynes et al. Proc. Nat'l Acad. Sci. USA 95:652-656 (1998). C1q bindingassays may also be carried out to confirm that the antibody is unable tobind C1q and hence lacks complement-dependent cytotoxicity (CDC)activity. See, e.g., C1q and C3c binding ELISA in WO2006/029879 andWO2005/100402. To assess complement activation, a CDC assay may beperformed (see, for example, Gazzano-Santoro et al., J. Immunol. Methods202:163 (1996); Cragg, M. S. et al., Blood 101:1045-1052 (2003); andCragg, M. S. and M. J. Glennie, Blood 103:2738-2743 (2004)). FcRnbinding and in vivo clearance/half-life Fc determinations can also beperformed using methods known in the art (see, e.g., Petkova, S. B. etal., Int'l. Immunol. 18(12): 1759-1769 (2006)).

Antibodies with reduced effector function include those withsubstitution of one or more of Fc region residues 238, 265, 269, 270,297, 327 and 329 (U.S. Pat. No. 6,737,056). Such Fc mutants include Fcmutants with substitutions at two or more of amino acid positions 265,269, 270, 297 and 327, including the so-called “DANA” Fc mutant withsubstitution of residues 265 and 297 to alanine (U.S. Pat. No.7,332,581).

Certain antibody variants with improved or diminished binding to FcRsare described (see, e.g., U.S. Pat. No. 6,737,056; WO 2004/056312, andShields et al., J. Biol. Chem. 9(2): 6591-6604 (2001)).

In certain embodiments, an antibody variant comprises an Fc region withone or more amino acid substitutions, which improve ADCC activity, e.g.,substitutions at positions 298, 333, and/or of the Fc region (EUnumbering of residues).

In some embodiments, alterations are made in the Fc region that resultin altered (i.e., either improved or diminished) C1q binding and/or CDCactivity, e.g., as described in U.S. Pat. No. 6,194,551, WO 99/51642,and Idusogie et al. J. Immunol. 164: 4178-4184 (2000).

Antibodies with increased half-lives and improved binding to theneonatal Fc receptor (FcRn), which is responsible for the transfer ofmaternal IgGs to the fetus (Guyer et al., J. Immunol. 117:587 (1976) andKim et al., J. Immunol. 24:249 (1994)), are described inUS2005/0014934A1 (Hinton et al.). Those antibodies comprise an Fc regionwith one or more substitutions therein which improve binding of the Fcregion to FcRn. Such Fc variants include those with substitutions at oneor more of Fc region residues: 238, 256, 265, 272, 286, 303, 305, 307,311, 312, 317, 340, 356, 360, 362, 376, 378, 380, 382, 413, 424 or 434,e.g., substitution of Fc region residue 434 (U.S. Pat. No. 7,371,826).See also Duncan & Winter, Nature 322:738-40 (1988); U.S. Pat. No.5,648,260; U.S. Pat. No. 5,624,821; and WO 94/29351 concerning otherexamples of Fc region variants.

Cysteine Engineered Antibody Variants

In certain embodiments, it may be desirable to create cysteineengineered antibodies, e.g., “thioMAbs,” in which one or more residuesof an antibody are substituted with cysteine residues.

In particular embodiments, the substituted residues occur at accessiblesites of the antibody. By substituting those residues with cysteine,reactive thiol groups are thereby positioned at accessible sites of theantibody and may be used to conjugate the antibody to other moieties,such as drug moieties or linker-drug moieties, to create animmunoconjugate, as described further herein. In certain embodiments,any one or more of the following residues may be substituted withcysteine: V205 (Kabat numbering) of the light chain; A118 (EU numbering)of the heavy chain; and S400 (EU numbering) of the heavy chain Fcregion. Cysteine engineered antibodies may be generated as described,e.g., in U.S. Pat. No. 7,521,541.

Methods of Diagnosis and Treatment

Antibodies of the present invention are designed to be used in methodsof diagnosis or treatment in human or animal subjects, preferably human.

Accordingly, further aspects of the invention provide methods ofdiagnosis comprising administration of an antibody as provided, with oneor more reagents e.g. conjugated to a detectable label such as FITC. Theantibody as provided may be used in the development of a rapid andreliable test for cancer cells derived from biopsied tissue. Forexample, the antibody may be used as a test for metastatic cancer cells,such as circulating tumour cells, which may be found circulating in bodyfluids such as blood or lymph. Other cancers of interest include breast,lung, gastric, head and neck, colorectal, renal, pancreatic, uterine,hepatic, bladder, endometrial and prostate cancers as well as lymphomas(e.g., non-Hodgkin's lymphoma, NHL) and leukemia (particularly acutemyeloid leukemia, AML).

Further aspects of the invention provide methods of treatment comprisingadministration of an antibody as provided, pharmaceutical compositionscomprising such an antibody, the antibody as described herein for use ina method of treatment, the antibody as described herein for use in amethod of treatment of particular clinical indications described herein,and use of such an antibody in the manufacture of a medicament foradministration, for example in a method of making a medicament orpharmaceutical composition comprising formulating the antibody with apharmaceutically acceptable excipient.

Clinical Indications

Clinical indications in which an antibody with high specificity forhuman Axl may be used to provide therapeutic benefit include anycondition in which Axl is overexpressed, or wherein Axl antagonism willprovide a clinical benefit. These include immune disorders,cardiovascular disorders, thrombosis, diabetes, immune checkpointdisorders, or proliferative diseases such as cancer, particularlymetastatic cancer. Furthermore, Axl is known to play a role in manycancers of epithelial origin.

Immune checkpoint disorders of interest include: Chronic viralinfections, Melanoma, Colorectal cancer, Breast cancer, Ovarian cancer,Non-small cell lung cancer (NSCLC), Prostate cancer, Renal cell cancer,Pancreatic cancer, Esophagus cancer, Bladder cancer, Myeloma, Kidneycancer, Bladder cancer, Brain tumor, and Lymphoma

Cancers of interest include: leukaemias such as but not limited to,acute leukemia, acute lymphocytic leukemia, acute myelocytic leukaemiassuch as myeloblastic, promyelocytic, myelomonocytic, monocytic,erythroleukaemia leukaemias and myelodysplastic syndrome, chronicleukaemias such as but not limited to, chronic myelocytic (granulocytic)leukemia, chronic lymphocytic leukemia, hairy cell leukemia;polycythemia vera; lymphomas such as but not limited to Hodgkin'sdisease, non-Hodgkin's disease; multiple myelomas such as but notlimited to smoldering multiple myeloma, nonsecretory myeloma,osteosclerotic myeloma, plasma cell leukemia, solitary plasmacytoma andextramedullary plasmacytoma; Waldenstrom's macroglobulinemia; monoclonalgammopathy of undetermined significance; benign monoclonal gammopathy;heavy chain disease; bone and connective tissue sarcomas such as but notlimited to bone sarcoma, osteosarcoma, chondrosarcoma, Ewing's sarcoma,malignant giant cell tumor, fibrosarcoma of bone, chordoma, periostealsarcoma, soft-tissue sarcomas, angiosarcoma (hemangiosarcoma),fibrosarcoma, Kaposi's sarcoma, leiomyosarcoma, liposarcoma,lymphangiosarcoma, metastatic cancers, neurilemmoma, rhabdomyosarcoma,synovial sarcoma; brain tumors such as but not limited to, glioma,glioblastoma, astrocytoma, brain stem glioma, ependymoma,oligodendroglioma, nonglial tumor, acoustic neurinoma,craniopharyngioma, medulloblastoma, meningioma, pineocytoma,pineoblastoma, primary brain lymphoma; breast cancer, including, but notlimited to, adenocarcinoma, lobular (small cell) carcinoma, intraductalcarcinoma, medullary breast cancer, mucinous breast cancer, tubularbreast cancer, papillary breast cancer, primary cancers, Paget'sdisease, and inflammatory breast cancer; adrenal cancer such as but notlimited to pheochromocytom and adrenocortical carcinoma; thyroid cancersuch as but not limited to papillary or follicular thyroid cancer,medullary thyroid cancer and anaplastic thyroid cancer; pancreaticcancer such as but not limited to, insulinoma, gastrinoma, glucagonoma,vipoma, somatostatin-secreting tumor, and carcinoid or islet cell tumor;pituitary cancers such as but limited to Cushing's disease,prolactin-secreting tumor, acromegaly, and diabetes insipius; eyecancers such as but not limited to ocular melanoma such as irismelanoma, choroidal melanoma, and cilliary body melanoma, andretinoblastoma; vaginal cancers such as squamous cell carcinoma,adenocarcinoma, and melanoma; vulvar cancer such as squamous cellcarcinoma, melanoma, adenocarcinoma, basal cell carcinoma, sarcoma, andPaget's disease; cervical cancers such as but not limited to, squamouscell carcinoma, and adenocarcinoma; uterine cancers such as but notlimited to endometrial carcinoma and uterine sarcoma; ovarian cancerssuch as but not limited to, ovarian epithelial carcinoma, borderlinetumor, germ cell tumor, and stromal tumor; esophageal cancers such asbut not limited to, squamous cancer, adenocarcinoma, adenoid cycticcarcinoma, mucoepidermoid carcinoma, adenosquamous carcinoma, sarcoma,melanoma, plasmacytoma, verrucous carcinoma, and oat cell (small cell)carcinoma; stomach cancers such as but not limited to, adenocarcinoma,fungating (polypoid), ulcerating, superficial spreading, diffuselyspreading, malignant lymphoma, liposarcoma, fibrosarcoma, andcarcinosarcoma; colon cancers; rectal cancers; liver cancers such as butnot limited to hepatocellular carcinoma and hepatoblastoma, gallbladdercancers such as adenocarcinoma; cholangiocarcinomas such as but notlimited to pappillary, nodular, and diffuse; lung cancers such asnon-small cell lung cancer (NSCLC), squamous cell carcinoma (epidermoidcarcinoma), adenocarcinoma, large-cell carcinoma and small-cell lungcancer (SCLC); testicular cancers such as but not limited to germinaltumor, seminoma, anaplastic, classic (typical), spermatocytic,nonseminoma, embryonal carcinoma, teratoma carcinoma, choriocarcinoma(yolk-sac tumor), prostate cancers such as but not limited to,adenocarcinoma, leiomyosarcoma, and rhabdomyosarcoma; genital cancerssuch as penile cancer; oral cancers such as but not limited to squamouscell carcinoma; basal cancers; salivary gland cancers such as but notlimited to adenocarcinoma, mucoepidermoid carcinoma, and adenoidcysticcarcinoma; pharynx cancers such as but not limited to squamous cellcancer, and verrucous; skin cancers such as but not limited to, basalcell carcinoma, squamous cell carcinoma and melanoma, superficialspreading melanoma, nodular melanoma, lentigo malignant melanoma, acrallentiginous melanoma; kidney cancers such as but not limited to renalcell cancer, adenocarcinoma, hypernephroma, fibrosarcoma, transitionalcell cancer (renal pelvis and/or uterer); Wilms' tumor; bladder cancerssuch as but not limited to transitional cell carcinoma, squamous cellcancer, adenocarcinoma, carcinosarcoma. In addition, cancers includemyxosarcoma, osteogenic sarcoma, endotheliosarcoma,lymphangioendotheliosarcoma, mesothelioma, synovioma, hemangioblastoma,epithelial carcinoma, cystadenocarcinoma, bronchogenic carcinoma, sweatgland carcinoma, sebaceous gland carcinoma, papillary carcinoma andpapillary adenocarcinomas. Preferably, the cancer is selected frombreast, melanoma, prostate, ovarian, colorectal, lung or glioma cancer.More preferably, the cancer is metastatic breast or lung cancer. Thetargeting and treatment of circulating tumour cells is envisaged.

The treatment of metastatic cancer depends on where the primary tumouris located. When breast cancer spreads to the lungs, for example, itremains a breast cancer and the treatment is determined by themetastatic cancer origin within the breast, not by the fact that it isnow in the lung. About 5 percent of the time, metastatic cancer isdiscovered but the primary tumour cannot be identified. The treatment ofthese metastatic cancers is dictated by their location rather than theirorigin. Metastatic cancers are named by the tissue of the originaltumour (if known). For example, a breast cancer that has spread to thebrain is called metastatic breast cancer to the brain.

Anti-Axl treatment in accordance with the present invention may be usedto provide clear benefit for patients with conditions where Axl isoverexpressed, or wherein Axl antagonism will provide a clinicalbenefit. Treatment may be given by injection (e.g. intravenously) or bylocal delivery methods. The antibody as provided may be used to directthe delivery of pharmaceutical compositions to the target tissue, orsystemically in order to target, for example, Circulating Tumour Cells(CTCs) or other metastatic cells.

In a further aspect of the invention, there is provided a method ofinhibiting Cancer Stem Cells in a subject, the method comprising ofcontacting the subject with an antibody (or conjugate thereof) asdescribed herein. Antibodies and conjugates for use in such a method arealso envisaged.

EGFR Antagonism

The invention also provides methods of inhibiting constitutive Axlactivation comprising administering to the individual an effectiveamount of any of the anti-Axl antibodies disclosed herein to inhibitconstitutive Axl.

In one aspect, the invention provides methods for treating a subjectsuffering from a cancer associated with an EGFR activating mutation oran EGFR gene amplification, wherein the subject has developed aresistance to treatment with an EGFR antagonist, comprising determiningwhether the subject has Axl expression, an Axl activating mutation or anAxl gene amplification, and administering to those subjects having anAxl activating mutation or an Axl gene amplification an EGFR antagonistand any of the anti-Axl antibodies described herein.

In one aspect, the invention provides methods for treating a subjectsuffering from a cancer associated with an EGFR activating mutation oran EGFR gene amplification, comprising: (i) monitoring a subject beingtreated with an EGFR antagonist to determine if the subject develops Axlexpression, an Axl activating mutation or an Axl gene amplification, and(ii) modifying the treatment regimen of the subject to include any ofthe anti-Axl antibodies described herein in addition to the EGFRantagonist where the subject has developed an Axl activating mutation oran Axl gene amplification.

In one aspect, the invention provides methods for treating a subjectsuffering from a cancer associated with an EGFR activating mutation oran EGFR gene amplification, comprising: (i) monitoring a subject beingtreated with EGFR antagonist to determine if the subject develops aresistance to the inhibitor, (ii) testing the subject to determinewhether the subject has Axl expression, an Axl activating mutation or anAxl gene amplification, and (iii) modifying the treatment regimen of thesubject to include any of the anti-Axl antibodies described herein inaddition to the EGFR antagonist where the subject has an Axl activatingmutation or an Axl gene amplification.

In one aspect, the invention provides methods for evaluating an EGFRantagonist, comprising: (i) monitoring a population of subjects beingtreated with an EGFR antagonist to identify those subjects that developa resistance to the therapeutic, (ii) testing the resistant subjects todetermine whether the subjects have Axl expression, an Axl activatingmutation or an Axl gene amplification, and (iii) modifying the treatmentregimen of the subjects to include any of the anti-Axl antibodiesdescribed herein in addition to the EGFR antagonist where the subjectshave Axl expression, an Axl activating mutation or an Axl geneamplification.

In one aspect, the invention provides methods for reducing EGFRphosphorylation in a cancer cell, wherein said cancer cell has acquiredresistance to an EGFR antagonist, and wherein said cell comprises an Axlactivating mutation or an Axl gene amplification, comprising the step ofcontacting the cell with any of the anti-Axl antibodies described hereinand an EGFR antagonist.

In one aspect, the invention provides methods for reducing PBK mediatedsignaling in a cancer cell, wherein said cancer cell has acquiredresistance to an EGFR antagonist, and wherein said cell comprises Axlexpression, an Axl activating mutation or an Axl gene amplification,comprising the step of contacting the cell with any of the anti-Axlantibodies described herein and an EGFR antagonist.

In one aspect, the invention provides methods for reducing EGFR-mediatedsignaling in a cancer cell, wherein said cancer cell has acquiredresistance to an EGFR antagonist, and wherein said cell comprises Axlexpression, an Axl activating mutation or an Axl gene amplification,comprising contacting the cell with any of the anti-Axl antibodiesdescribed herein and an EGFR antagonist.

In one aspect, the invention provides methods for restoring sensitivityof a cancer cell to an EGFR antagonist, wherein said cancer cell hasacquired resistance to an EGFR antagonist, and wherein said cellcomprises Axl expression, an Axl activating mutation or an Axl geneamplification, comprising contacting the cell with any of the anti-Axlantibodies described herein and an EGFR antagonist.

In one aspect, the invention provides methods for reducing growth orproliferation of a cancer cell, wherein said cancer cell has acquiredresistance to an EGFR antagonist, and wherein said cell comprises Axlexpression, an Axl activating mutation or an Axl gene amplification,comprising the step of contacting the cell with any of the anti-Axlantibodies described herein and an EGFR antagonist.

In one aspect, the invention provides methods for increasing apoptosisof a cancer cell, wherein said cancer cell has acquired resistance to anEGFR antagonist, and wherein said cell comprises Axl expression, an Axlactivating mutation or an Axl gene amplification, comprising the step ofcontacting the cell with any of the anti-Axl antibodies described hereinand an EGFR antagonist.

In one aspect, the invention provides methods for reducing resistance ofa cancer cell to an EGFR antagonist, wherein said cancer cell hasacquired resistance to an EGFR antagonist, and wherein said cellcomprises an Axl activating mutation or an Axl gene amplification,comprising the step of contacting the cell with any of the anti-Axlantibodies described herein and an EGFR antagonist.

In one aspect, the invention provides methods for treating acquired EGFRantagonist resistance in a cancer cell, wherein said cell comprises anAxl activating mutation or an Axl gene amplification, comprisingcontacting the cell with any of the anti-Axl antibodies described hereinand an EGFR antagonist.

In some embodiments, the cancer cell is any EGFR-driven cancer. In someembodiments, the cancer cell comprises an EGFR activating mutation. Insome embodiments, the cancer cell comprises an EGFR gene amplification.In some embodiments, the EGFR gene amplification is at least 2-fold. Insome embodiments, the Axl amplification is at least 2-fold. In someembodiments, the cancer cell comprises an EGFR gene mutation associatedwith increased resistance to an EGFR antagonist. In some embodiments,the EGFR gene mutation associated with increased resistance to an EGFRantagonist is a T790M mutation of EGFR.

In some embodiments, the EGFR antagonist is a small moleculetherapeutic, a nucleic acid therapeutic, or a protein therapeutic. Insome embodiments, the EGFR antagonist is an antibody, an antisensemolecule, or a small molecule kinase inhibitor. In some embodiments, theEGFR antagonist is an EGFR kinase inhibitor selected from the groupconsisting of: gefitinib, erlotinib, cetuximab, pantinumumab. In someembodiments, the EGFR antagonist is an anti-EGFR antibody selected fromthe group consisting of: cetuximab, panitumumab. In some embodiments,the nucleic acid therapeutic is a siRNA molecule.

In one aspect, the invention provides methods for identifying a subjectas a candidate for treatment with an EGFR antagonist and any of theanti-Axl antibodies described herein, wherein said subject has beentreated with an EGFR antagonist and suffers from cancer that hasacquired resistance to said EGFR antagonist, comprising detecting Axlexpression, an Axl activating mutation or Axl gene amplification in acancer cell from said subject.

In one aspect, the invention provides methods for identifying a subjectwho is being treated with an EGFR antagonist and who is at risk foracquiring resistance to said EGFR antagonist, comprising detecting thepresence of Axl expression, an Axl activating mutation or an Axl geneamplification in a cancer cell from said subject, wherein the presenceof said Axl expression, Axl activating mutation or Axl geneamplification indicates a risk for acquiring said resistance.

In one aspect, the invention provides methods for treating a subjectsuffering from a cancer that is resistant to treatment with an EGFRantagonist, comprising administering to the subject an EGFR antagonistand any of the anti-Axl antibodies described herein.

In one aspect, the invention provides methods for treating a subjectsuffering from a cancer associated with an EGFR activating mutation oran EGFR gene amplification, wherein the subject has developed aresistance to treatment with an EGFR antagonist, comprising determiningwhether the subject has Axl expression, such as elevated Axl levelsand/or activity, and administering to those subjects having Axlexpression, such as elevated Axl activity an EGFR antagonist and any ofthe anti-Axl antibodies described herein.

In one aspect, the invention provides methods for treating a subjectsuffering from a cancer associated with an EGFR activating mutation oran EGFR gene amplification, comprising: (i) monitoring a subject beingtreated with an EGFR antagonist to determine if the subject develops Axlexpression, such as elevated levels and/or Axl activity, and (ii)modifying the treatment regimen of the subject to include any of theanti-Axl antibodies described herein in addition to the EGFR antagonistwhere the subject has developed Axl expression, such as elevated Axllevels and/or activity.

In one aspect, the invention provides methods for treating a subjectsuffering from a cancer associated with an EGFR activating mutation oran EGFR gene amplification, comprising: (i) monitoring a subject beingtreated with EGFR antagonist to determine if the subject develops aresistance to the inhibitor, (ii) testing the subject to determinewhether the subject has Axl expression, such as elevated Axl levelsand/or activity, and (iii) modifying the treatment regimen of thesubject to include any of the anti-Axl antibodies described herein inaddition to the EGFR antagonist where the subject has elevated Axllevels and/or activity.

In another aspect, the invention provides a method for (i) restoring thesensitivity of a cancer cell to an EGFR antagonist, (ii) reducingresistance of a cancer cell to an EGFR antagonist, and/or (iii) treatingacquired EGFR antagonist resistance in a cancer cell, by contacting thecell with an EGFR antagonist and any of the anti-Axl antibodiesdescribed herein.

In exemplary embodiments, the cancer cell has acquired a resistance toan EGFR antagonist and comprises elevated levels of Axl activity and/orexpression, e.g., associated with an activating mutation in the Axlgene, an Axl gene amplification, or Gas6 mediated Axl activation. Themethods disclosed herein may be used to restore the sensitivity, reducethe resistance, and/or treat an acquired resistance, of a cancer cell.

In another aspect, the invention provides a method for reducing growthand/or proliferation of a cancer cell, or increasing apoptosis of acancer cell, by contacting the cell with an EGFR antagonist and any ofthe anti-Axl antibodies described herein. In exemplary embodiments, thecancer cell has acquired a resistance to an EGFR antagonist andcomprises elevated Axl activity and/or expression, e.g., associated withan activating mutation in the Axl gene, an Axl gene amplification, orGas6 mediated Axl activation.

Pharmaceutical Compositions

Antibodies of the present invention will usually be administered in theform of a pharmaceutical composition, which may comprise at least onecomponent in addition to the antibody.

Thus pharmaceutical compositions according to the present invention, andfor use in accordance with the present invention, may comprise, inaddition to active ingredient, a pharmaceutically acceptable excipient,carrier, buffer, stabiliser or other materials well known to thoseskilled in the art. Such materials should be non-toxic and should notinterfere with the efficacy of the active ingredient. The precise natureof the carrier or other material will depend on the route ofadministration, which may be oral, or by injection, e.g. intravenous.The pharmaceutical compositions may be for human or animal usage inhuman and veterinary medicine.

Examples of such suitable excipients for the various different forms ofpharmaceutical compositions described herein may be found in the“Handbook of Pharmaceutical Excipients”, 2nd Edition, (1994), Edited byA Wade and P J Weller.

Acceptable carriers or diluents for therapeutic use are well known inthe pharmaceutical art, and are described, for example, in Remington'sPharmaceutical Sciences, Mack Publishing Co. (A. R. Gennaro edit. 1985).Examples of suitable carriers include lactose, starch, glucose,methylcellulose, magnesium stearate, mannitol, sorbitol and the like.Examples of suitable diluents include ethanol, glycerol, water andbuffered saline.

The choice of pharmaceutical carrier, excipient or diluent can beselected with regard to the intended route of administration andstandard pharmaceutical practice. The pharmaceutical compositions maycomprise as, or in addition to, the carrier, excipient or diluent anysuitable binder(s), lubricant(s), suspending agent(s), coating agent(s),solubilising agent(s), buffer(s), flavouring agent(s), surface activeagent(s), thickener(s), preservative(s) (including anti-oxidants) andthe like, and substances included for the purpose of rendering theformulation isotonic with the blood of the intended recipient.

Examples of suitable binders include starch, gelatin, natural sugarssuch as glucose, anhydrous lactose, free-flow lactose, beta-lactose,corn sweeteners, natural and synthetic gums, such as acacia, tragacanthor sodium alginate, carboxymethyl cellulose and polyethylene glycol.

Examples of suitable lubricants include sodium oleate, sodium stearate,magnesium stearate, sodium benzoate, sodium acetate, sodium chloride andthe like. Preservatives, stabilizers, dyes and even flavoring agents maybe provided in the pharmaceutical composition. Examples of preservativesinclude sodium benzoate, sorbic acid and esters of p hydroxybenzoicacid. Antioxidants and suspending agents may be also used.

Pharmaceutical formulations include those suitable for oral, topical(including dermal, buccal and sublingual), rectal or parenteral(including subcutaneous, intradermal, intramuscular and intravenous),nasal and pulmonary administration, e.g., by inhalation. The formulationmay, where appropriate, be conveniently presented in discrete dosageunits and may be prepared by any of the methods well known in the art ofpharmacy. All methods include the step of bringing into association anactive compound with liquid carriers or finely divided solid carriers orboth and then, if necessary, shaping the product into the desiredformulation. Pharmaceutical formulations suitable for oraladministration wherein the carrier is a solid are most preferablypresented as unit dose formulations such as boluses, capsules or tabletseach containing a predetermined amount of active agent. A tablet may bemade by compression or moulding, optionally with one or more accessoryingredients. Compressed tablets may be prepared by compressing in asuitable machine an active agent in a free-flowing form such as a powderor granules optionally mixed with a binder, lubricant, inert diluent,lubricating agent, surface-active agent or dispersing agent. Mouldedtablets may be made by moulding an active agent with an inert liquiddiluent. Tablets may be optionally coated and, if uncoated, mayoptionally be scored. Capsules may be prepared by filling an activeagent, either alone or in admixture with one or more accessoryingredients, into the capsule shells and then sealing them in the usualmanner. Cachets are analogous to capsules wherein an active agenttogether with any accessory ingredient(s) is sealed in a rice paperenvelope. An active agent may also be formulated as dispersiblegranules, which may for example be suspended in water beforeadministration, or sprinkled on food. The granules may be packaged,e.g., in a sachet. Formulations suitable for oral administration whereinthe carrier is a liquid may be presented as a solution or a suspensionin an aqueous or non-aqueous liquid, or as an oil-in-water liquidemulsion.

Formulations for oral administration include controlled release dosageforms, e.g., tablets wherein an active agent is formulated in anappropriate release—controlling matrix, or is coated with a suitablerelease—controlling film. Such formulations may be particularlyconvenient for prophylactic use.

Pharmaceutical formulations suitable for rectal administration whereinthe carrier is a solid are most preferably presented as unit dosesuppositories. Suitable carriers include cocoa butter and othermaterials commonly used in the art. The suppositories may beconveniently formed by admixture of an active agent with the softened ormelted carrier(s) followed by chilling and shaping in moulds.

Pharmaceutical formulations suitable for parenteral administrationinclude sterile solutions or suspensions of an active agent in aqueousor oleaginous vehicles.

Injectable preparations may be adapted for bolus injection or continuousinfusion. Such preparations are conveniently presented in unit dose ormulti-dose containers which are sealed after introduction of theformulation until required for use. Alternatively, an active agent maybe in powder form which is constituted with a suitable vehicle, such assterile, pyrogen-free water, before use.

An active compound may also be formulated as long-acting depotpreparations, which may be administered by intramuscular injection or byimplantation, e.g., subcutaneously or intramuscularly. Depotpreparations may include, for example, suitable polymeric or hydrophobicmaterials, or ion-exchange resins. Such long-acting formulations areparticularly convenient for prophylactic use.

Formulations suitable for pulmonary administration via the buccal cavityare presented such that particles containing an active compound anddesirably having a diameter in the range of 0.5 to 7 microns aredelivered in the bronchial tree of the recipient. As one possibilitysuch formulations are in the form of finely comminuted powders which mayconveniently be presented either in a pierceable capsule, suitably of,for example, gelatin, for use in an inhalation device, or alternativelyas a self-propelling formulation comprising an active agent, a suitableliquid or gaseous propellant and optionally other ingredients such as asurfactant and/or a solid diluent. Suitable liquid propellants includepropane and the chlorofluorocarbons, and suitable gaseous propellantsinclude carbon dioxide. Self-propelling formulations may also beemployed wherein an active agent is dispensed in the form of droplets ofsolution or suspension.

Such self-propelling formulations are analogous to those known in theart and may be prepared by established procedures. Suitably they arepresented in a container provided with either a manually-operable orautomatically functioning valve having the desired spraycharacteristics; advantageously the valve is of a metered typedelivering a fixed volume, for example, 25 to 100 microliters, upon eachoperation thereof.

As a further possibility, an active agent may be in the form of asolution or suspension for use in an atomizer or nebuliser whereby anaccelerated airstream or ultrasonic agitation is employed to produce afine droplet mist for inhalation.

Formulations suitable for nasal administration include preparationsgenerally similar to those described above for pulmonary administration.When dispensed such formulations should desirably have a particlediameter in the range 10 to 200 microns to enable retention in the nasalcavity; this may be achieved by, as appropriate, use of a powder of asuitable particle size or choice of an appropriate valve. Other suitableformulations include coarse powders having a particle diameter in therange 20 to 500 microns, for administration by rapid inhalation throughthe nasal passage from a container held close up to the nose, and nasaldrops comprising 0.2 to 5% w/v of an active agent in aqueous or oilysolution or suspension.

Pharmaceutically acceptable carriers are well known to those skilled inthe art and include, but are not limited to, 0.1 M and preferably 0.05 Mphosphate buffer or 0.8% saline. Additionally, such pharmaceuticallyacceptable carriers may be aqueous or non-aqueous solutions,suspensions, and emulsions. Examples of non-aqueous solvents arepropylene glycol, polyethylene glycol, vegetable oils such as olive oil,and injectable organic esters such as ethyl oleate. Aqueous carriersinclude water, alcoholic/aqueous solutions, emulsions or suspensions,including saline and buffered media. Parenteral vehicles include sodiumchloride solution, Ringer's dextrose, dextrose and sodium chloride,lactated Ringer's or fixed oils. Preservatives and other additives mayalso be present, such as, for example, antimicrobials, antioxidants,chelating agents, inert gases and the like.

Formulations suitable for topical formulation may be provided forexample as gels, creams or ointments. Such preparations may be appliede.g. to a wound or ulcer either directly spread upon the surface of thewound or ulcer or carried on a suitable support such as a bandage,gauze, mesh or the like which may be applied to and over the area to betreated.

Liquid or powder formulations may also be provided which can be sprayedor sprinkled directly onto the site to be treated, e.g. a wound orulcer. Alternatively, a carrier such as a bandage, gauze, mesh or thelike can be sprayed or sprinkle with the formulation and then applied tothe site to be treated.

According to a further aspect of the invention, there is provided aprocess for the preparation of a pharmaceutical or veterinarycomposition as described above, the process comprising bringing theactive compound(s) into association with the carrier, for example byadmixture. In general, the formulations are prepared by uniformly andintimately bringing into association the active agent with liquidcarriers or finely divided solid carriers or both, and then if necessaryshaping the product. The invention extends to methods for preparing apharmaceutical composition comprising bringing an agent into associationwith a pharmaceutically or veterinary acceptable carrier or vehicle.

Administration

The pharmaceutical compositions of the present invention may be adaptedfor oral, rectal, nasal, intrabronchial, topical (including buccal andsublingual), vaginal or parenteral (including subcutaneous,intramuscular, intravenous, intra-arterial and intradermal),intraperitoneal or intrathecal administration. Preferably, theformulation is an intravenously or subcutaneously administeredformulation.

The formulations may conveniently be presented in unit dosage form,i.e., in the form of discrete portions containing a unit dose, or amultiple or sub-unit of a unit dose. By way of example, the formulationsmay be in the form of tablets and sustained release capsules, and may beprepared by any method well known in the art of pharmacy.

Formulations for oral administration in the present invention may bepresented as: discrete units such as capsules, gellules, drops, cachets,pills or tablets each containing a predetermined amount of the activeagent; as a powder or granules; as a solution, emulsion or a suspensionof the active agent in an aqueous liquid or a non-aqueous liquid; or asan oil-in-water liquid emulsion or a water-in-oil liquid emulsion; or asa bolus etc. Preferably, these compositions contain from 1 to 250 mg andmore preferably from 10-100 mg, of active ingredient per dose.

For compositions for oral administration (e.g. tablets and capsules),the term “acceptable carrier” includes vehicles such as commonexcipients e.g. binding agents, for example syrup, acacia, gelatin,sorbitol, tragacanth, polyvinylpyrrolidone (Povidone), methylcellulose,ethylcellulose, sodium carboxymethylcellulose,hydroxypropyl-methylcellulose, sucrose and starch; fillers and carriers,for example corn starch, gelatin, lactose, sucrose, microcrystallinecellulose, kaolin, mannitol, dicalcium phosphate, sodium chloride andalginic acid; and lubricants such as magnesium stearate, sodium stearateand other metallic stearates, glycerol stearate stearic acid, siliconefluid, talc waxes, oils and colloidal silica. Flavouring agents such aspeppermint, oil of wintergreen, cherry flavouring and the like can alsobe used. It may be desirable to add a colouring agent to make the dosageform readily identifiable. Tablets may also be coated by methods wellknown in the art.

A tablet may be made by compression or moulding, optionally with one ormore accessory ingredients. Compressed tablets may be prepared bycompressing in a suitable machine the active agent in a free flowingform such as a powder or granules, optionally mixed with a binder,lubricant, inert diluent, preservative, surface-active or dispersingagent. Moulded tablets may be made by moulding in a suitable machine amixture of the powdered compound moistened with an inert liquid diluent.The tablets may be optionally be coated or scored and may be formulatedso as to provide slow or controlled release of the active agent.

Other formulations suitable for oral administration include lozengescomprising the active agent in a flavoured base, usually sucrose andacacia or tragacanth; pastilles comprising the active agent in an inertbase such as gelatin and glycerin, or sucrose and acacia; andmouthwashes comprising the active agent in a suitable liquid carrier.

Other forms of administration comprise solutions or emulsions which maybe injected intravenously, intraarterially, intrathecally,subcutaneously, intradermally, intraperitoneally or intramuscularly, andwhich are prepared from sterile or sterilisable solutions. Injectableforms typically contain between 10-1000 mg, preferably between 10-250mg, of active ingredient per dose.

The pharmaceutical compositions of the present invention may also be inform of suppositories, pessaries, suspensions, emulsions, lotions,ointments, creams, gels, sprays, solutions or dusting powders.

An alternative means of transdermal administration is by use of a skinpatch. For example, the active ingredient can be incorporated into acream consisting of an aqueous emulsion of polyethylene glycols orliquid paraffin. The active ingredient can also be incorporated, at aconcentration of between 1 and 10% by weight, into an ointmentconsisting of a white wax or white soft paraffin base together with suchstabilisers and preservatives as may be required.

Alternative formulation strategies may provide preparations suitable fororal or suppository route. The route of administration may be determinedby the physicochemical characteristics of the treatment, by specialconsiderations for the disease, to optimise efficacy or to minimiseside-effects.

A further mode of administration employs pre-coating of, or otherwiseincorporation into, indwelling devices, for which the optimal amount ofantibody will be determined by means of appropriate experiments.

An antibody molecule in some preferred embodiments of the invention is amonomeric fragment, such as Fab or scFv. Such antibody fragments mayhave the feature of a relatively short half-life.

Dosage

A person of ordinary skill in the art can easily determine anappropriate dose of one of the instant compositions to administer to asubject without undue experimentation. Typically, a physician willdetermine the actual dosage which will be most suitable for anindividual patient and it will depend on a variety of factors includingthe activity of the specific agent employed, the metabolic stability andlength of action of that agent, the age, body weight, general health,sex, diet, mode and time of administration, rate of excretion, drugcombination, the severity of the particular condition, and theindividual undergoing therapy.

In accordance with the present invention, compositions provided may beadministered to individual patients. Administration is preferably in a“therapeutically effective amount”, this being sufficient to showbenefit to a patient. Such benefit may be at least amelioration of atleast one symptom. The actual amount administered, and the rate andtime-course of administration, will depend on the nature and severity ofwhat is being treated. Prescription of treatment, e.g., decisions ondosage etc., is within the responsibility of general practitioners andother medical doctors. Appropriate doses of antibody are well known inthe art; see Ledermann J. A. et al. (1991) Int. J. Cancer 47: 659-664;Bagshawe, K. D. et al. (1991) Antibody, Immunoconjugates andRadiopharmaceuticals 4: 915-922.

The precise dose will depend upon a number of factors, including whetherthe antibody is for diagnosis or for treatment, the size and location ofthe area to be treated, the precise nature of the antibody (e.g. wholeantibody, antibody fragment or diabody), and the nature of anydetectable label or other molecule attached to the antibody. A typicalantibody dose may be administered as a bolus intravenously. Other modesof administration include intravenous infusion over several hours, toachieve a similar total cumulative dose. This is a dose for a singletreatment of an adult patient, which may be proportionally adjusted forchildren and infants, and also adjusted for other antibody formats inproportion to molecular weight. Treatments may be repeated at daily,twice-weekly, weekly or monthly intervals, at the discretion of thephysician.

The dosages disclosed herein are exemplary of the average case. Therecan of course be individual instances where higher or lower dosageranges are merited, and such are within the scope of this invention.

In accordance with this invention, an effective amount of agent may beadministered to inhibit Axl. Of course, this dosage amount will furtherbe modified according to the type of administration of the agent. Forexample, to achieve an “effective amount” for acute therapy, parenteraladministration is preferred. An intravenous infusion of the compound in5% dextrose in water or normal saline, or a similar formulation withsuitable excipients, is most effective, although an intramuscular bolusinjection is also useful. Typically, the parenteral dose will be about0.01 to about 100 mg/kg; preferably between 0.1 and 20 mg/kg, in amanner to maintain the concentration of drug in the plasma at aconcentration effective to inhibit a kinase or saturate the targetreceptor. The agents may be administered one to four times daily at alevel to achieve a total daily dose of about 0.4 to about 400 mg/kg/day.The precise amount of an active agent which is therapeuticallyeffective, and the route by which such agent is best administered, isreadily determined by one of ordinary skill in the art by comparing theblood level of the agent to the concentration required to have atherapeutic effect.

The agents of this invention may also be administered orally to thepatient, in a manner such that the concentration of drug is sufficientto achieve one or more of the therapeutic indications disclosed herein.Typically, a pharmaceutical composition containing the agent isadministered at an oral dose of between about 0.1 to about 50 mg/kg in amanner consistent with the condition of the patient. Preferably the oraldose would be about 0.5 to about 20 mg/kg.

The agents of this invention may be tested in one of several biologicalassays to determine the concentration of an agent which is required tohave a given pharmacological effect.

Combination Therapy

A composition may be administered alone or in combination with othertreatments, either simultaneously or sequentially dependent upon thecondition to be treated. For example, the antibodies of the invention orconjugates thereof may be used as an anti-cancer monotherapy or incombination therapy with other cancer treatments as mentioned below.Other treatments may include the administration of suitable doses ofpain relief drugs such as non-steroidal anti-inflammatory drugs (e.g.aspirin, ibuprofen or ketoprofen) or opiates such as morphine, oranti-emetics.

In a preferred aspect the antibodies of the invention (or conjugatesthereof) are administered in combination with an immune checkpointmodulator (ICM), such as an immune checkpoint inhibitor (ICI).Typically, an ICM is an agent, such as an aptamer or an antibody, whichbinds the targeted receptor.

The ICM used in combination with an antibody of the invention (orconjugate thereof) may be any suitable ICM known in the art. Inparticular, suitable immune checkpoint modulating agents include:

-   -   CTLA-4 targeting agents, including Ipilimumab and Tremelimumab.    -   PD-1 targeting agents, including Pembrolizumab, Mivolumab and        AMP-514/MEDI0680.    -   BD-L1 targeting agents, including MPDL3280A, MED14736,        MSB0010718C and BMS-936559.    -   4-1BB targeting agents, including Urelumab and PF-05082566.    -   OX-40 targeting agents, including MED16469, MED16383 (rOX40L)        and MOXR0916.    -   GITR targeting agents, including TRX518.    -   CD27 targeting agents, including CDX-1127.    -   CD40 targeting agents, including CP-870,893.    -   LAG3 targeting agents, including BMS-986016.

Immune checkpoints, which are inhibitory pathways in the immune system,may be co-opted by tumours to induce immune resistance. The use ofagents to block or modulate immune checkpoints, including T-cellstimulatory and inhibitory receptors and dendritic cell stimulatoryreceptors, and thus to reduce or reverse the immune resistance of thecancer, is an important avenue in cancer research.

T-cell stimulatory receptors which may be modulated through the use ofICMs include CD28, ICOS, 4-1 BB, OX40, GITR, CD27, TWEAKR, HVEM andTIM-1. T-cell inhibitory receptors which maybe modulated through the useof ICMs include PD-L1, CTLA-4, PD-1, BTLA, TIM-3, VISTA, LAG-3 andTIGIT. Dendritic cell stimulatory receptors which may be modulatedthrough the use of ICMs include CD40 and 4-1BB.

Where a combination of ICMs are used in conjunction with an antibody ofthe invention (or conjugate thereof), all of the ICMs may targetinhibitory receptors, all of the ICMs used may target stimulatoryreceptors, or a combination of inhibitory receptor and stimulatoryreceptor targeting ICMs may be used.

Thus, there is thus provided an antibody of the invention (or conjugatethereof) for use a method of treating of cancer, wherein the treatmentfurther comprises administering one or more ICM. Similarly, there isprovided the use of an antibody of the invention (or conjugate thereof)in the manufacture of a medicament for the treatment of cancer, whereinthe treatment further comprises administering one or more immunecheckpoint modulating agents.

There is also provided an antibody of the invention (or conjugatethereof) for use in a method of treating cancer, or the use of such anantibody (or conjugate thereof) in the manufacture of a medicament forthe treatment of cancer, wherein the treatment further comprises one ormore immune checkpoint modulating agents selected from Ipilimumab,Tremelimumab, Pembrolizumab, Mivolumab, AMP-514/MEDI0680, MPDL3280A,MED14736, MSB0010718C, BMS-936559, Urelumab, PF-05082566, MED16469,MED16383 (rOX40L), MOXR0916, TRX518, CDX-1127, CP-870,893 andBMS-986016.

The antibody of the invention (or conjugate thereof) may be administeredbefore the one or more ICM, simultaneously with the one or more ICM, orafter the one or more ICM.

There is also provided an antibody of the invention (or conjugatethereof) for use in the treatment of cancer, or the use of such anantibody (or conjugate thereof) in the manufacture of a medicament forthe treatment of cancer, wherein the treatment further comprises one ormore ICM, and wherein the cancer is selected from lung cancer, melanoma,breast cancer, ovarian cancer or carcinoma.

Suitable Agents for Use in Combination Therapy

-   -   These include alkylating agents, e.g., alkyl sulfonates such as        busulfan;    -   nitrogen mustards such as chlorambucil, cyclophosphamide,        estramustine, ifosfamide, mechlorethamine, melphalan, and        uramustine, ethyleneimine derivatives such as thiotepa;    -   nitrosoureas such as carmustine, lomustine, and streptozocin,        triazenes such as dacarbazine, procarbazine, and temozolamide;    -   platinum compounds such as cisplatin, carboplatin, oxaliplatin,        satraplatin, and picoplatin onnaplatin, tetraplatin,        sprioplatin, iproplatin, chloro(diethylenediamino)-platinum (II)        chloride, dichloro(ethylenediamino)-platinum (II),        diamino(2-ethylmalonato)platinum (II),        (1,2-diaminocyclohexane)malonatoplatinum (II),        (4-carboxyphthalo)-(1,2-diaminocyclohexane)platinum (II),        (1,2-diaminocyclohexane)-(isocitrato)platinum (II), and        (1,2-diaminocyclohexane)-cis-(pyruvato)platinum (II);    -   anti-metabolites, including antifolates such as methotrexate,        permetrexed, raltitrexed, and trimetrexate;    -   pyrimidine analogs such as azacitidine, capecitabine,        cytarabine, edatrexate, floxuridine, fluorouracil, gemcitabine,        and troxacitabine;    -   purine analogs such as cladribine, chlorodeoxyadenosine,        clofarabine, fludarabine, mercaptopurine, pentostatin, and        thioguanine;    -   natural products, including antitumor antibiotics such as        bleomycin, dactinomycin, mithramycin, mitomycin, mitoxantrone,        porfiromycin, and anthracyclines such as daunorubicin,        doxorubicin, epirubicin, idarubicin, and valrubicin;    -   mitotic inhibitors such as the vinca alkaloids vinblastine,        vinvesir, vincristine, vindesine, and vinorelbine;    -   enzymes such as L-asparaginase and PEG-L-asparaginase;    -   microtubule polymer stabilizers such as the taxanes paclitaxel        and docetaxel;    -   topoisomerase I inhibitors such as the camptothecins irinotecan        and topotecan; topoisomerase II inhibitors such as        podophyllotoxin, amsacrine, etoposide, teniposide, losoxantrone        and actinomycin;    -   hormones and hormone antagonists, including androgens such as        fluoxymesterone and testolactone, anti-androgens such as        bicalutamide, cyproterone, flutamide, and nilutamide;    -   corticosteroids such as dexamethasone and prednisone;    -   aromatase inhibitors such as aminoglutethimide, anastrozole,        exemestane, formestane, and letrozole;    -   estrogens such as diethylstilbestrol;    -   anti-estrogens such as fulvestrant, raloxifene, tamoxifen, and        toremifine;    -   luteinising hormone-releasing hormone (LHRH) agonists and        antagonists such as abarelix, buserelin, goserelin, leuprolide,        histrelin, desorelin, nafarelin acetate and triptorelin;    -   progestins such as medroxyprogesterone acetate and megestrol        acetate, and thyroid hormones such as levothyroxine and        liothyronine;    -   PKB pathway inhibitors, including perifosine, enzastaurin        hydrochloride, and triciribine;    -   PI3K inhibitors such as semaphore and SF1126;    -   mTOR inhibitors such as rapamycin and analogues;    -   CDK inhibitors, including seliciclib, alvocidib, and        7-hydroxystaurosporine;    -   COX-2 inhibitors, including celecoxib;    -   HDAC inhibitors, including trichostatin A, suberoylanilide        hydroxamic acid, and chlamydocin;    -   DNA methylase inhibitors, including temozolomide; and    -   miscellaneous agents, including altretamine, arsenic trioxide,        thalidomide, lenalidomide, gallium nitrate, levamisole,        mitotane, hydroxyurea, octreotide, procarbazine, suramin,        photodynamic compounds such as methoxsalen and sodium porfimer,        and proteasome inhibitors such as bortezomib.    -   Molecular targeted therapy agents including:    -   functional therapeutic agents, e.g., gene therapy agents;    -   antisense therapy agents;    -   tyrosine kinase inhibitors such as erlotinib hydrochloride,        gefitinib, imatinib mesylate, and semaxanib;    -   RAF inhibitors such as sorafenib;    -   gene expression modulators such as the retinoids and rexinoids,        for example adapalene, bexarotene, trans-retinoic acid,        9-cis-retinoic acid, and N-(4-hydroxyphenyl)retinamide;    -   phenotype-directed therapy agents, including monoclonal        antibodies such as alemtuzumab, bevacizumab, cetuximab,        ibritumomab tiuxetan, rituximab, and trastuzumab;    -   immunotoxins such as emtansine, radioimmunoconjugates such as        1-tositumobab, binding agents, such as aptamers, targeting any        one of the molecular targets herein described,    -   and    -   cancer vaccines.    -   Biologic therapy agents including:    -   interferons such as interferon-[alpha]2a and        interferon-[alpha]2b, and interleukins such as aldesleukin,        denileukin diftitox, and oprelvekin. Axl inhibiting agents        including        1-(6,7-dihydro-5H-benzo[6,7]cyclohepta[1,2-c]pyridazin-3-yl)-N3-((7-(S)-pyrrolidin-1-yl)-6,7,8,9-tetrahydro-5H-benzo[7]annulene-2-yl)-1H-1,2,4-triazole-3,5-diamine        (BGB324/R428), CH5451098 (Roche) and Axl inhibitors described in        PCT/US07/089177, PCT/US2010/021275 and PCT/EP2011/004451,        incorporated herein by reference.

In addition to these agents intended to act against cancer cells,anticancer therapies include the use of protective or adjunctive agents,including:

cytoprotective agents such as amifostine, and dexrazoxane;phosphonates such as pamidronate and zoledronic acid; andstimulating factors such as epoetin, darbeopetin, filgrastim,PEG-filgrastim, and sargramostim.

Many combination chemotherapeutic regimens are known to the art, such ascombinations of carboplatin/paclitaxel, capecitabine/docetaxel,fluorauracil/levamisole, fluorauracil/leucovorin,methotrexate/leucovorin, and trastuzumab/paclitaxel, alone or in furthercombination with carboplatin, and the like.

Throughout the specification, preferably the methods described hereinare performed in vitro or ex vivo.

The present invention provides a method comprising causing or allowingbinding of an antibody as provided herein to Axl. As noted, such bindingmay take place in vivo, e.g. following administration of an antibody, ornucleic acid encoding an antibody, or it may take place in vitro, forexample in ELISA, Western blot analysis, immunocytochemistry,immunohistochemistry, immunoprecipitation or affinity chromatography.

The amount of antibody bound to Axl receptor may be determined.Quantitation may be related to the amount of the antigen in a testsample, which may be of diagnostic interest.

The reactivity of antibody in a sample may be determined by anyappropriate means. Radioimmunoassay (RIA) is one possibility.Radioactively labelled antigen is mixed with unlabelled antigen (thetest sample) and allowed to bind to the antibody. Bound antigen isphysically separated from unbound antigen and the amount of radioactiveantigen bound to the antibody determined. The more antigen there is inthe test sample the less radioactive antigen will bind to the antibody.A competitive binding assay may also be used with non-radioactiveantigen, using antigen or an analogue linked to a reporter molecule. Thereporter molecule may be a fluorochrome, phosphor or laser dye withspectrally isolated absorption or emission characteristics. Suitablefluorochromes include fluorescein, rhodamine, phycoerythrin and TexasRed. Suitable chromogenic dyes include diaminobenzidine.

Other reporters include macromolecular colloidal particles orparticulate material such as latex beads that are coloured, magnetic orparamagnetic, and biologically or chemically active agents that candirectly or indirectly cause detectable signals to be visually observed,electronically detected or otherwise recorded. These molecules may beenzymes which catalyse reactions that develop or change colours or causechanges in electrical properties, for example. They may be molecularlyexcitable, such that electronic transitions between energy states resultin characteristic spectral absorptions or emissions. They may includechemical entities used in conjunction with biosensors. Biotin/avidin orbiotin/streptavidin and alkaline phosphatase detection systems may beemployed.

Further reporters include DNA tags. These tags may be readily quantifiedby, for example, qPCR.

The signals generated by individual antibody-reporter conjugates may beused to derive quantifiable absolute or relative data of the relevantantibody binding in samples (normal and test).

The present invention also provides the use of an antibody as above formeasuring antigen levels in a competition assay, that is to say a methodof measuring the level of antigen in a sample by employing an antibodyas provided by the present invention in a competition assay. This may bewhere the physical separation of bound from unbound antigen is notrequired. Linking a reporter molecule to the antibody so that a physicalor optical change occurs on binding is one possibility. The reportermolecule may directly or indirectly generate detectable, and preferablymeasurable, signals. The linkage of reporter molecules may be directlyor indirectly, covalently, e.g. via a peptide bond or non-covalently.Linkage via a peptide bond may be as a result of recombinant expressionof a gene fusion encoding antibody and reporter molecule.

The present invention also provides for measuring levels of antigendirectly, by employing an antibody according to the invention forexample in a biosensor system.

The mode of determining binding is not a feature of the presentinvention and those skilled in the art are able to choose a suitablemode according to their preference and general knowledge.

The present invention further extends to an antibody which competes forbinding to Axl with any antibody which both binds the antigen andcomprises an antibody variable domain (either VH or VL or both)including a CDR with amino acid substantially as set out herein or avariable domain with amino acid sequence substantially as set outherein. Competition between the antibodies may be assayed easily invitro, for example by tagging a specific reporter molecule to onebinding member which can be detected in the presence of other untaggedbinding member(s), to enable identification of antibodies which bind thesame epitope or an overlapping epitope. Competition may be determinedfor example using ELISA or flow cytometry. Alternatively, competingantibodies may be identified via surface plasmon resonance (SPR)technique using Biacore instrument, as described in Example 5.

In testing for competition, a peptide fragment of the antigen may beemployed, especially a peptide including an epitope of interest. Apeptide having the epitope sequence plus one or more amino acids ateither end may be used. Such a peptide may be said to “consistessentially” of the specified sequence. Antibodies according to thepresent invention may be such that their binding for antigen isinhibited by a peptide with or including the sequence given. In testingfor this, a peptide with either sequence plus one or more amino acidsmay be used.

Antibodies which bind a specific peptide may be isolated for examplefrom a phage display library by panning with the peptide(s).

The present invention further provides an isolated nucleic acid encodingan antibody of the present invention. Nucleic acid includes DNA and RNA.In a preferred aspect, the present invention provides a nucleic acidwhich codes for a CDR, VH or VL domain of the invention as definedabove.

The present invention also provides constructs in the form of plasmids,vectors, transcription or expression cassettes which comprise at leastone polynucleotide as above.

The present invention also provides a recombinant host cell whichcomprises one or more constructs as above. A nucleic acid encoding anyCDR, VH or VL domain, or antibody as provided, itself forms an aspect ofthe present invention, as does a method of production of the encodedproduct, which method comprises expression from encoding nucleic acidtherefor. Expression may conveniently be achieved by culturing underappropriate conditions recombinant host cells containing the nucleicacid. Following production by expression, a VH or VL domain, or antibodymay be isolated and/or purified using any suitable technique known inthe art.

Antibodies, VH and/or VL domains, and encoding nucleic acid moleculesand vectors according to the present invention may be provided isolatedand/or purified, e.g. from their natural environment, in substantiallypure or homogeneous form, or, in the case of nucleic acid, free orsubstantially free of nucleic acid or genes of an origin other than thesequence encoding a polypeptide with the required function. Nucleic acidaccording to the present invention may comprise DNA or RNA and may bewholly or partially synthetic. Reference to a nucleotide sequence as setout herein encompasses a DNA molecule with the specified sequence, andencompasses a RNA molecule with the specified sequence in which U issubstituted for T, unless context requires otherwise.

Systems for cloning and expression of a polypeptide in a variety ofdifferent host cells are well known. Suitable host cells includebacteria, mammalian cells, yeast, baculovirus, and insect cell systems.Mammalian cell lines available in the art for expression of aheterologous polypeptide include Chinese hamster ovary cells (CHO), HeLacells, baby hamster kidney (BHK) cells, NS0 and SP2/0 mouse myelomacells, YB2/0 rat myeloma cells, human cell lines HEK-293 and PER.C6 andmany others. A common, preferred bacterial host is E. coli.

The expression of antibodies and antibody fragments in prokaryotic cellssuch as E. coli is well established in the art. For a review, see forexample Plückthun, A. Bio/Technology 9: 545-551 (1991). Expression ineukaryotic cells in culture is also available to those skilled in theart as an option for production of an antibody, see for reviews, forexample Ref, M.E. (1993) Curr. Opinion Biotech. 4: 573-576; Trill J. J.et al. (1995) Curr. Opinion Biotech 6: 553-560.

Suitable vectors can be chosen or constructed, containing appropriateregulatory sequences, including promoter sequences, terminatorsequences, polyadenylation sequences, enhancer sequences, marker genesand other sequences as appropriate. Vectors may be plasmids, viral e.g.phage, or phagemid, as appropriate (Sambrook and Russell, 2001,Molecular Cloning: a Laboratory Manual: 3^(rd) edition, Cold SpringHarbor Laboratory Press). Many known techniques and protocols formanipulation of nucleic acid, for example in preparation of nucleic acidconstructs, mutagenesis, sequencing, introduction of DNA into cells andgene expression, and analysis of proteins, are described in detail inCurrent Protocols in Molecular Biology, Second Edition, Ausubel et al.eds., John Wiley & Sons, 1992.

Thus, a further aspect of the present invention provides a host cellcontaining nucleic acid as disclosed herein. A still further aspectprovides a method comprising introducing such nucleic acid into a hostcell. The introduction may employ any available technique. Foreukaryotic cells, suitable techniques may include calcium phosphatetransfection, DEAE-Dextran, electroporation, liposome-mediatedtransfection and transduction using retrovirus or other virus, e.g.vaccinia or, for insect cells, baculovirus. For bacterial cells,suitable techniques may include calcium chloride transformation,electroporation and transfection using bacteriophage.

The introduction may be followed by causing or allowing expression fromthe nucleic acid, e.g. by culturing host cells under conditions forexpression of the gene.

In one embodiment, the nucleic acid of the invention is integrated intothe genome (e.g. chromosome) of the host cell. Integration may bepromoted by inclusion of sequences which promote recombination with thegenome, in accordance with standard techniques.

The present invention also provides a method which comprises using aconstruct as stated above in an expression system in order to express anantibody or polypeptide as above.

Aspects and embodiments of the present invention will now be illustratedby way of example with reference to the following experimentation.

All documents cited anywhere in this specification are incorporated byreference.

STATEMENTS OF INVENTION

The following paragraphs describe a number of specifically envisionedembodiments and combinations of the present invention.

1. An antibody that binds Axl and which comprises:

-   -   an antibody VH domain selected from the group consisting of the        1H12 VH domain (SEQ ID NO.3) and a VH domain comprising a VH        CDR3 with the amino acid sequence of SEQ ID NO.7 and optionally        one or more VH CDR's with an amino acid sequence selected from        SEQ ID NO.6 and SEQ ID NO.5; and/or    -   an antibody VL domain selected from the group consisting of the        1H12 VL domain (SEQ ID NO. 4) and a VL domain comprising one or        more VL CDR's with an amino acid sequence selected from SEQ ID        NO.8, SEQ ID NO.9 and SEQ ID NO.10.

2. An antibody according to paragraph 1 comprising an antibody VH domaincomprising the VH CDR's with the amino acid sequences of SEQ ID NO.5,SEQ ID NO.6 and SEQ ID NO.7, which antibody competes for binding to Axlwith an Axl binding domain of an antibody comprising the 1H12 VH domain(SEQ ID NO. 3) and the 1H12 VL domain (SEQ ID NO. 4).

3. An antibody according to paragraph 1 or paragraph 2 comprising the1H12 VH domain (SEQ ID NO. 3).

4. An antibody according to paragraph 3 comprising the 1H12 VL domain(SEQ ID NO. 4)

5. A variant of an antibody according to any one of paragraphs 1 to 4,wherein the variant comprises one or more amino acid sequencealterations in one or more framework regions and/or one or more CDRs.

6. An antibody according to any one of paragraphs 1 to 5 that binds Axlwith affinity equal to or better than the affinity of an Axlantigen-binding site formed by the 1H12 VH domain (SEQ ID NO. 3) and the1H12 VL domain (SEQ ID NO. 4), the affinity of the antibody and theaffinity of the antigen-binding site being as determined under the sameconditions.

7. An antibody according to any one of paragraphs 1 to 6 that comprisesan scFv antibody molecule.

8. An antibody according to any one of paragraphs 1 to 6 that comprisesan antibody constant region.

9. An antibody according to paragraph 8 that comprises a whole antibody.

10. An antibody according to any one of paragraphs 1 to 6 wherein theantibody is an antigen-binding antibody fragment, such as a singledomain antibody, Fv, scFv, dsFv, Fd, Fab, F(ab′)2, minibody, diabody,single-chain diabody, tandem scFv, TandAb, bi-body, tri-body,kappa(lambda)-body, BiTE, DVD-Ig, SIP, SMIP, or DART.

11. An antibody according to any one of paragraphs 1 to 10 whichcomprises additional amino acids providing a further functionalcharacteristic in addition to the ability to bind antigen.

12. An antibody according to any one of paragraphs 1 to 11 which bindsAxl with a K_(D) no greater than 5×10⁻¹¹ M.

13. An antibody according to any one of paragraphs 1 to 11 which bindsAxl with a K_(D) no greater than 1.5×10⁻¹¹ M.

14. An antibody according to any one of paragraphs 1 to 13 which bindsAxl with a k_(off) no greater than 2×10⁻⁵ s⁻¹.

15. An antibody according to any one of paragraphs 1 to 14 which bindsAxl with a k_(off) no greater than 3×10⁻⁶ s⁻¹.

16. An antibody according to any one of paragraphs 1 to 15 wherein theAxl is human Axl.

17. An antibody according to any one of paragraphs 1 to 16 whichspecifically binds primate Axl.

18. An antibody according to any one of paragraphs 1 to 17 which:

-   -   (i) binds murine Axl with a K_(D) greater than 10⁻³ M;    -   (ii) binds human Mer with a K_(D) greater than 10⁻³ M; and/or    -   (iii) binds human Tyro3 with a K_(D) greater than 10⁻³ M.

19. An antibody according to any one of paragraphs 1 to 18 wherein theantibody is an Axl agonist.

20. An antibody according to paragraph 19 wherein Axl signalling is atleast 10% greater.

21. An antibody according to any one of paragraphs 1 to 20 wherein theantibody is a chimeric antibody.

22. An antibody according to any one of paragraphs 1 to 20 wherein theantibody is a humanised antibody.

23. An antibody according to any one of paragraphs 1 to 22 wherein theantibody binds:

-   -   (i) the same epitope as the 1H12 antibody, or    -   (ii) an epitope which overlaps with the epitope bound by the        1H12 antibody.

24. An antibody according to any one of paragraphs 1 to 23 wherein theantibody is internalised following binding to Axl present on a cellsurface.

25. An antibody according to any one of paragraphs 1 to 24 which isconjugated to a detectable label, enzyme, or toxin, optionally via apeptidyl bond or linker.

26. An antibody according to paragraph 25 wherein the toxin is selectedfrom the group comprising MMAE and MMAF.

27. An antibody according to paragraph 25 wherein the detectable labelis FITC.

28. An isolated nucleic acid which comprises a nucleotide sequenceencoding an antibody or antibody VH or VL domain of an antibodyaccording to any one of paragraphs 1 to 24.

29. A host cell transformed with nucleic acid according to paragraph 28.

30. A method of producing a antibody or antibody VH or VL domain, themethod comprising culturing host cells according to paragraph 29 underconditions for production of said antibody or antibody VH or VL domain.

31. A method according to paragraph 30 further comprising isolatingand/or purifying said antibody or antibody VH or VL variable domain.

32. A method according to paragraph 30 or paragraph 31 furthercomprising formulating the antibody or antibody VH or VL variable domaininto a composition including at least one additional component.

33. A method of obtaining an antibody that binds Axl, the methodcomprising

-   -   providing by way of addition, deletion, substitution or        insertion of one or more amino acids in the amino acid sequence        of the 1H12 VH domain (SEQ ID NO. 3) one or more VH domains each        of which is an amino acid sequence variant of the 1H12 VH        domain, optionally combining one or more VH domain amino acid        sequence variants thus provided with one or more VL domains to        provide one or more VH/VL combinations; and/or    -   providing by way of addition, deletion, substitution or        insertion of one or more amino acids in the amino acid sequence        of the 1H12 VL domain (SEQ ID NO. 4) a VL domain which is an        amino acid sequence variant of the 1H12 VL domain, and combining        one or more VL domain amino acid sequence variants thus provided        with one or more VH domains to provide one or more VH/VL domain        combinations;        and    -   testing the VH domain amino acid sequence variants or VHNL        combination or combinations for to identify a antibody that        binds Axl.

34. A method of obtaining an antibody that binds Axl, which methodcomprises:

providing starting nucleic acids encoding one or more VH domains whicheither comprise a CDR3 to be replaced or lack a CDR3 encoding region,and combining said starting nucleic acid with a donor nucleic acidencoding the VH CDR3 amino acid sequence of SEQ ID NO.7 such that saiddonor nucleic acid is inserted into the CDR3 region in the startingnucleic acid, so as to provide product nucleic acids encoding VHdomains; or

-   -   providing starting nucleic acids encoding one or more VL domains        which either comprise a CDR3 to be replaced or lack a CDR3        encoding region, and combining said starting nucleic acid with a        donor nucleic acid encoding the VL CDR3 amino acid sequence of        SEQ ID NO.10 such that said donor nucleic acid is inserted into        the CDR3 region in the starting nucleic acid, so as to provide        product nucleic acids encoding VL domains;    -   expressing the nucleic acids of said product nucleic acids        encoding VH domains and optionally combining the VH domains thus        produced with one or more VL domains to provide VH/VL        combinations, and/or expressing the nucleic acids of said        product nucleic acids encoding VL domains and combining the VL        domains thus produced with one or more VH domains to provide        VH/VL combinations;    -   selecting an antibody comprising a VH domain or a VH/VL        combination that binds Axl; and        recovering said antibody that binds Axl and/or nucleic acid        encoding the antibody that binds Axl.

35. A method according to paragraph 33 or paragraph 34 wherein theantibody that binds Axl is an antibody fragment comprising a VH domainand a VL domain.

36. A method according to paragraph 35 wherein the antibody fragment isan scFv antibody molecule.

37. A method according to paragraph 35 wherein the antibody fragment isan Fab antibody molecule.

38. A method according to paragraph 36 or paragraph 37 furthercomprising providing the VH domain and/or the VL domain of the antibodyfragment in a whole antibody.

39. A method according to any one of paragraphs 33 to 38 furthercomprising formulating the antibody that binds Axl or an antibody VH orVL variable domain of the antibody that binds Axl into a compositionincluding at least one additional component.

40. A method according to any one of paragraphs 30 to 39 furthercomprising binding a antibody that binds Axl to Axl or a fragment ofAxl.

41. A method comprising binding an antibody that binds Axl according toany one of paragraphs 1 to 27 to Axl or a fragment of Axl.

42. A method according to paragraph 40 or paragraph 41 wherein saidbinding takes place in vitro.

43. A method according to any one of paragraphs 40 to 42 comprisingdetermining the amount of binding of antibody to Axl or a fragment ofAxl.

44. A method according to any one of paragraphs 30 to 39 furthercomprising use of the antibody in the manufacture of a medicament fortreatment of a disease or disorder characterised by overexpression ofAxl.

45. An antibody according to any one of paragraphs 1 to 27, or animmunoconjugate thereof, in combination with another therapeutic agent.

46. A composition comprising an antibody according to any one ofparagraphs 1 to 27, or an immunoconjugate thereof, in conjunction with apharmaceutically acceptable excipient.

47. A composition according to paragraph 46 further comprising anothertherapeutic agent.

48. An antibody according to paragraph 45 or a composition according toparagraph 47 wherein the other therapeutic agent is an immune checkpointmodulator (ICM), such as an immune checkpoint inhibitor (ICI).

49. An antibody according to any one of paragraphs 1 to 27, 45, or 48,or the composition according to any one of paragraphs 46 to 48, for usein a method of treatment.

50. An antibody or composition according to paragraph 49 for use in amethod of treating a proliferative disease.

51. An antibody or composition according to paragraph 40 where theproliferative disease is cancer, such as AML.

52. An antibody or composition according to paragraph 51 where thecancer is metastatic cancer.

53. Use of an antibody according to any one of paragraphs 1 to 27, 45,or 48, or the composition according to any one of paragraphs 46 to 48,in the manufacture of a medicament for treatment of a disease ordisorder characterised by overexpression of Axl.

54. A method of treatment of a disease or disorder characterised byoverexpression of Axl, the method comprising administering an antibodyaccording to any one of paragraphs 1 to 27, 45, or 48, or thecomposition according to any one of paragraphs 46 to 48, to a patientwith the disease or disorder or at risk of developing the disease ordisorder.

55. A method according to paragraph 50 wherein the antibody directs thedelivery of a pharmaceutical composition to target metastatic cancercells.

56. Use of an antibody according to any one of paragraphs 1 to 27, 45,or 48 and one or more reagents that allow determination of the bindingof said antibody to metastatic cancer cells, in the manufacture of adiagnostic agent for the detection of a disease or disordercharacterised by overexpression of Axl.

57. A method of diagnosis of a disease or disorder characterised byoverexpression of Axl, the method comprising administering an antibodyaccording to any one of paragraphs 1 to 27, 45, or 48, or thecomposition according to any one of paragraphs 46 to 48, and one or morereagents that allow determination of the binding of said antibody tometastatic cancer cells, to a patient with the disease or disorder or atrisk of developing the disease or disorder.

58. A diagnostic kit comprising an antibody according to any one ofparagraphs 1 to 27, 45, or 48 and one or more reagents that allowdetermination of the binding of said member to metastatic cancer cells.

59. A kit comprising an antibody according to any one of paragraphs 1 to27, 45, or 48, or the composition according to any one of paragraphs 46to 48.

60. A pharmaceutical composition comprising as active principle anantibody according to paragraphs 1 to 27 in an effective amount, inconjunction with a pharmaceutically acceptable excipient.

EXAMPLES Example 1: Generation of Mouse Anti-Axl Monoclonal Antibody

Monoclonal antibodies (MAb) against human Axl receptor were generated byimmunization of immunocompetent OF1 mice (Charles River) with arecombinant antigen comprising an extracellular domain of human Axlfused to human IgG1 Fc domain (rhAxl-Fc; R&D Systems).

Spleen cells from mice showing presence of rhAxl-specific antibodies inthe blood were used for fusion with mouse myeloma cells according tostandard protocols. The cells were cultured in plates (10⁵ cells perwell) with hypoxanthine-aminopterin-thymidine (HAT) medium for hybridomaselection. After twelve days of selection, the supernatants wereharvested and tested for Axl binding in enzyme-linked immunosorbentassay (ELISA) and flow cytometry. Five positive clones, showing thehighest antigen-binding activity after the second round of subcloning bylimited dilution, were expanded for large scale antibody production invitro. The MAbs were purified from the cell culture supernatants byProtein G affinity chromatography.

The antibody clone 1H12 showing specific binding to Axl⁺ cells in flowcytometry (FIG. 1) was selected for further characterization.

For flow cytometry, the adherent cells in culture were washed with PBS,detached by trypsin (0.25%) treatment for 1 min and hitting culture dishfor full detachment. Trypsin was quenched by adding into the tissueflask the complete medium followed by washing the cells with PBS. Duringthe washing steps, the cells were collected by centrifugation at 200 gfor 5 min. The antibody was diluted for total concentration in PBScontaining 0.02% bovine serum albumin (BSA). Cell staining was performedusing 200 μL of cell suspension comprising 10⁵ cells for 20 min at roomtemperature. After two washing steps with PBS 0.02% BSA, the cells wereresuspended in 200 μL and kept on ice before analysis on Accuri C6 flowcytometer (BD Biosciences).

Example 2: Mouse Monoclonal Antibody 1H12 does not Cross-React withOther Members of Human Tam Receptor Family

All binding experiments were performed using Biacore 3000 instrument (GEHealthcare) at 25° C. The soluble recombinant antigens corresponding tothe members of human TAM receptor family, Axl (rhAxl-Fc chimera; R&DSystems, Cat. no. 154-AL), Mer (rhMer-Fc chimera; R&D Systems, Cat. no.891-MR) and Tyro3 (rhTyro3/Dtk-Fc chimera; R&D Systems, Cat. no. 859-DK)were immobilized on the surface of CM5 sensor chip using amine couplingat the surface density of 393.0, 303.6 and 364.0 resonance units (RU),respectively. The Biacore run was performed in an automatic mode usingBinding analysis wizard. The sample containing MAb 1H12 at concentration10 μg/mL in HBS-EP buffer (GE Healthcare) was injected over the surfaceswith immobilized antigens at flow rate of 30 μL/min for 3 min(association) followed by 5 min dissociation.

The results shown in FIG. 2 demonstrate specific interaction with humanAxl and no binding to recombinant human Mer and Tyro3 antigens.

Example 3: Mouse Monoclonal Antibody 1H12 does not Cross-React withMouse Axl

The binding experiments were performed using Biacore 3000 instrument (GEHealthcare) at 25° C. The soluble recombinant antigens corresponding tohuman Axl (rhAxl-Fc chimera; R&D Systems, Cat. no. 154-AL), mouse Axl(rmAxl-Fc chimera; R&D Systems, R&D Systems; Cat. no. 854-AX) and humanTyro3 (rhTyro3/Dtk-Fc chimera; R&D Systems, Cat. no. 859-DK) wereimmobilized on the surface of CM5 sensor chip using amine coupling atthe surface density of 1,308.0, 2,115.9 and 1,429.0 RU, respectively.The Biacore run was performed in an automatic mode using BindingAnalysis wizard.

The sample containing either MAb 1H12 or recombinant mouse (rm)Axl-ligand Gas6 (R&D Systems, Cat. no. 986-GS/CF) at concentration 10μg/mL in HBS-EP buffer (GE Healthcare) was injected over the surfaceswith immobilized antigens at flow rate of 30 μL/min for 3 min(association) followed by 5 min dissociation.

The results shown in FIG. 3 demonstrate specific interaction of MAb 1H12with human Axl and no binding to recombinant mouse Axl and human Merantigens (FIG. 3, upper panel). In contrast, mouse Gas6, used as acontrol, demonstrated strong binding to both human and mouse Axl andsomewhat weaker binding to human Tyro3 (FIG. 3, lower panel).

Example 4: Affinity Determination of Mouse Monoclonal Antibody 1H12

Affinity determination of anti-Axl antibody 1H12 was performed at 25° C.by surface plasmon resonance measurements using Biacore 3000 instrument(GE Healthcare). As a solid antigen-coated surface, the sensor chip CM5with immobilized rhAxl-Fc chimera (R&D Systems, Cat. no. 154-AL) atdensity 190 RU was used.

For the kinetics measurements, different concentrations of anti-Axl MAb1H12 (from 1.3 to 666.7 nM) in HBS-EP buffer (Biacore, Cat. no.BR-1001-88) were injected at flow rate of 30 μL/min with 3 min injectiontime followed by 5 min dissociation (buffer alone). After each cycle,the surface was regenerated by 30 sec injection of a regenerationsolution (10 mM HCl, 1 M NaCl) at flow rate 50 μL/min.

The mass transfer control experiments demonstrated absence ofsignificant mass transfer limitations for MAb 1H12. An additional,linked reactions control experiment did not reveal linked reactions forMAb 1H12, since the dissociation phases were practically identical afterinjection for 1, 3 or 20 min or one analyte concentration (1.8 μM or 270μg/mL). The kinetic association (on-rate, k_(on)) and dissociation(off-rate, k_(off)) rates were calculated using BIAevaluation softwareand 1:1 Langmuir binding model. The equilibrium dissociation constant(K_(D)) was calculated as the k_(off)/k_(on) ratio. The half-life(t_(1/2)) of the formed antibody-antigen complexes was calculated as theIn2/k_(off) ratio.

As shown in FIG. 4, the mouse MAb 1H12 demonstrated very high affinity(K_(D)=4.98×10⁻¹¹ M) mainly due to a very slow dissociation rate(k_(off)=1.07×10⁻⁵ 1/s) which resulted in 18 hr half-life of the1H12/Axl complex.

Example 5: Mouse Monoclonal Antibody 1H12 does not Block Binding of Gas6to Axl

The competitive binding study was performed using Biacore 3000instrument (GE Healthcare) and Binding Analysis wizard with severalcycles of two samples injection. As a first sample, a saturatingconcentration of MAb 1H12 (1.8 μM or 270 μg/mL) was injected over thesurface of the CM5 sensor chip coated with rhAxl-Fc (using aminecoupling) for 3 min at flow rate of 30 μL/min followed by 2.5 minstabilization (HBS-EP buffer alone) before the injection of the secondsample. The following second samples were used: recombinant human (rh)Gas6 (R&D Systems, Cat. no. 885-GS), recombinant mouse (rm) Gas6 (R&DSystems, Cat. no. 986-GS/CF) and a panel of anti-Axl antibodies(MAb1,2,3); all at concentration 25 μg/mL. As a control, MAb 1H12 wasused as a second sample under the same conditions (25 μg/mL). The secondsample was injected for 3 min, followed by 2.5 min stabilization (bufferalone) and regeneration of the surface by 30 sec injection of aregeneration solution (10 mM HCl, 1 M NaCl) at flow rate 50 μL/min.

The results shown in FIG. 5 demonstrated that the MAb 1H12 did notcompete for Axl binding with Gas6 (both human and mouse) and any otheranti-Axl antibody used in the experiment.

Example 6: Mouse Monoclonal Antibody 1H12 Binds to Denatured BothReduced and Non-Reduced Axl in Western Blot Analysis

For Western blot analysis, the recombinant human (rh) Axl-Fc chimera(R&D Systems, Cat. no. 154-AL) with a predicted molecular mass of 71.7kDa (corresponds to 100-110 kDa in SDS-PAGE under reducing conditions)and rhMer-Fc (R&D Systems, Cat. no. 891-MR) with a predicted mol. massof 78.9 kDa (corresponds to 100-110 kDa in SDS-PAGE under reducingconditions) were used as antigens. The samples containing the antigenswere denatured in presence or absence of the reducing agent (LifeTechnologies) and loaded into the wells of NuPAGE 3-8% Tris-Acetatepolyacrylamide (PAA) gel, 1.0 mm×12 well (Invitrogen). As the molecularweight markers, SeeBlue PIus2 Prestained MW markers (Novex LC5925) wereused.

The electrophoresis was performed using Tris-Acetate SDS running bufferunder the recommended conditions (Life Technologies) and the proteinswere transfer on nitrocellulose membrane, as described for 2 gels in amanual for XCell II™ Blot Module (Invitrogen) using the transfer bufferwith 20% methanol. The membrane was incubated in 10 mL of blockingbuffer, TBS/0.1% Tween20 (TBST) with 5% skimmed milk, for 1 hr at roomtemperature followed by overnight incubation in 5 mL of incubationbuffer (TBST with 3% skimmed milk) containing 1 μg/mL MAb 1H12 at 4° C.The membrane was washed three times for 5 min each with 10 mL of TBSTfollowed by 1 hr incubation with goat-anti mouse IgG (H+L)HRP-conjugated secondary antibody (1:3000) in 5 mL of incubation bufferwith gentle rolling at room temperature. Afterwards, the membrane waswashed three times for 5 min in 10 mL of TBST and twice with 10 mL ofTBS buffer. The membrane was incubated with 1 mL ECL substrate for 1 minat room temperature. The excess of substrate solution was aspirated theblot was developed using ChemiDoc™ XRS+ imager (Bio Rad) and Image labsoftware.

The results shown in FIG. 6 demonstrated that the antibody 1H12specifically interacts with both reduced and non-reduced denatured Axlantigen. No binding to rhMer-Fc was detected. The results indicate theMAb 1H12 recognizes linear epitope on extracellular part of Axlreceptor.

Example 7: Mouse Monoclonal Antibody 1H12 Binds to Denatured BothReduced and Non-Reduced Axl Receptor Expressed on Cell Surface in itsNatural Environment

Cell lysates from both Axl⁺ and Axl⁻ cell lines, NCI-H1299 (non-smallcell lung carcinoma, NSCLC) and LNCaP (prostatic adenocarcinoma),respectively, were prepared according to the standard protocols. Thecell lysate aliquots were denatured in presence or absence of thereducing agent (Life Technologies) and loaded into the wells of NuPAGE3-8% Tris-Acetate polyacrylamide (PAA) gel, 1.0 mm×12 well (Invitrogen).The SDS-PAGE and Western blot analysis were performed essentially asdescribed in EXAMPLE 6.

The results shown in FIG. 7 demonstrated specific interaction of MAb1H12 with Axl receptor (both reduced and non-reduced) present in Axl⁺NCI-H1299 cells. No interaction with other cellular proteins present ineither Axl⁺ or Axl⁻ cells was observed.

Example 8: Sequencing of Mouse Monoclonal Antibody 1H12

The hybridoma 1H12 cells were propagated under the standard conditions.5×10⁶ cells were used for mRNA isolation and cDNA synthesis according tothe standard protocols. For PCR amplification of the genes encodingheavy and light chain variable regions (VH and VL, respectively), MouseIgG Library Primer Set (Progen, Heidelberg, Germany, Cat. no. F2010) wasused. PCR amplification using different primer combinations resulted in14 sequences from PCR using 7 different primer combinations for the VHgene and in 7 sequences from PCR using 4 different primer combinationsfor the VL gene. The sequences of the clones VH5 C9-3 and VK4 G4-1 wereselected for further work on the basis of highest homology with thecorresponding germline sequences, as determined by nucleotide alignmentwith IMGT database.

The amino acid sequences of the 1H12 VH and VL domains are shown in FIG.8.

Example 9: Anti-Axl Mouse Monoclonal Antibody 1H12 Showed Weak or NoReaction with Normal Human Tissues in Immunohistochemistry

In a validation experiment, the optimal protocol and concentration forthe antibody 1H12 was determined. For this work, frozen pellets of Axl⁺and Axl⁻ cells were used. The antibody was tested at concentrations from0.05 μg/mL to 16.0 μg/mL (16, 8, 4, 2, 1, 0.5, 0.1, and 0.05 μg/mL). TheMAb 1H12 showed moderate to strong reaction in the Axl⁺ cells from 8down to 1 μg/mL; at 0.5 μg/mL the reaction was moderate. The optimalconcentration of 1 μg/mL was, therefore, set to be used in the tissuecross-reactivity (TCR) study. At this concentration, no reaction wasseen in the Axl-negative cells.

The TCR study was performed using commercial frozen tissue microarrays(TMA) purchased from BioChain (prod. no. T6234701-2). All tissues weredelivered from BioChain as cryo-sectioned, acetone-fixed frozen TMA.Experiments were performed as follows: the cryo-sectioning (8 μm) wasair-dried at room temperature overnight, and fixed in acetone for 10 minbefore they were blocked in 5% goat normal serum (JacksonImmunoResearch, 005-000-121) for 30 min. The sections were then stainedwith a primary antibody (1H12) in PBS with 5% goat normal serum for 1hr, before they were washed three times in PBS. Subsequently, thesections were stained with EnVision mouse (Dako, K4001) for 30 min.Finally, the sections were washed three times in Tris-HCl, before theywere stained with 3,3′-Diaminobenzidine (DAB) stain for 5 min. Imageswere taken using HTX imaging. Staining intensity was judged as: negative(0), weak reaction (1+), moderate reaction (2+), or strong reaction(3+). The results of normal human TCR are shown in TABLE 2.

The antibody 1H12 demonstrated weak-to-moderate or moderate reaction incells of lymph node and spleen (membrane staining). The local moderatereaction was also seen in liver—possibly in Kuppfer cells (membranestaining). Some local moderate or strong intracellular reaction was seenin epithelial cells of pancreas. The following tissues showed nospecific positive staining: adrenal, bone marrow, various brain tissuesand spinal cord, colon, endothelium/aorta, esophagus, fallopian tube,heart, kidney, lung, ovary, placenta, prostate, skin, spinal cord,striated muscle, stomach, testis, thymus, thyroid, ureter and uterus.

TABLE 2 Tissue Binding of MAb 1H12 Adrenal (1) Negative Adrenal (2)Negative Adrenal (3) Negative Bone marrow (1) 1-2+ background in somecell type Bone marrow (2) 1-2+ background in some cell type Bone marrow(3) 1-2+ background in some cell type Breast (1) Negative Breast (2)Negative Breast (3) Negative Brain cerebellum (1) Negative Braincerebellum (2) Negative Brain cerebellum (3) Negative Brain cortex (1)Negative Brain cortex (2) Negative Brain cortex (3) Negative Brainpituitary (1) Negative Brain pituitary (2) Negative Brain pituitary (3)Negative Colon (1) 2-3+ in mucin of epithelial cells (unspecific) Colon(2) Negative (no epithelium in section) Colon (3) Negative (noepithelium in section) Endothelium, aorta (1) Negative Endothelium,aorta (2) Negative Endothelium, aorta (3) Negative Esophagus (1)Negative Esophagus (2) Negative Esophagus (3) Negative Fallopian tube(1) Negative Fallopian tube (2) Negative Fallopian tube (3) NegativeHeart (1) Negative (some local unspecific background) Heart (2) Negative(some local unspecific background) Heart (3) Negative (some localunspecific background) Kidney (1) Negative (some unspecific background)Kidney (2) Negative (some unspecific background) Kidney (3) Negative(some unspecific background) Liver (1) 2+, possibly in Kuppfermacrophages Liver (2) 2+, possibly in Kuppfer macrophages Liver (3) 2+,possibly in Kuppfer macrophages Lung (1) 2-3+ local, probably unspecificLung (2) 2-3+ local, probably unspecific Lung (3) 2-3+ local, probablyunspecific Lymph node (1) 1-2+ in many cells Lymph node (2) 1-2+ in manycells Lymph node (3) 1-2+ in many cells Ovary (1) Negative Ovary (2)Negative Ovary (3) Negative Pancreas (1) 2+ local in epithelial cellsPancreas (2) Negative Pancreas (3) 3+ local Placenta (1) NegativePlacenta (2) Negative Placenta (3) Negative Prostate (1) NegativeProstate (2) Negative Prostate (3) Negative Skin (1) Negative Skin (2)Negative Skin (3) Negative Spinal cord (1) Negative Spinal cord (2)Negative Spinal cord (3) Negative Spleen (1) 2+ in many cells Spleen (2)2+ in many cells Spleen (3) 2+ in many cells Striated muscle (1)Negative Striated muscle (2) Negative Striated muscle (3) NegativeStomach (1) Negative Stomach (2) Negative Stomach (3) Negative Testis(1) Negative Testis (2) Negative Testis (3) Negative Thymus (1) NegativeThymus (2) Negative Thymus (3) Negative Thyroid (1) Negative Thyroid (2)Negative Thyroid, (3) Negative Ureter (1) Negative Ureter (2) NegativeUreter (3) Negative Uterus, endometrium (1) Negative Uterus, endometrium(2) Negative Uterus, endometrium (3) Negative Uterus, cervix (1)Negative Uterus, cervix (2) Negative Uterus, cervix (3) Negative

Example 10: Generation and Testing Chimeric Monoclonal Antibody 1H12

The VH and VL sequences retrieved from the murine hybridoma 1H12 wereused for generation of the synthetic genes with codon optimization forexpression in mammalian cells (GeneArt). These mouse VH and VL geneswere ligated in frame with the genetic elements encoding constantdomains of the human IgG1 heavy and light (C-kappa) chains,respectively, in an expression vector suitable for antibody productionin mammalian cells. Production of the chimeric (mouse variable/humanconstant) IgG1 antibodies was achieved by transient expression inChinese Hamster Ovary (CHO) cells followed by purification using ProteinA affinity chromatography. The purified chimeric antibody (>95% purity)was analyzed for binding to Axl-positive breast cancer cell lineMDA-MB-231 in flow cytometry. For comparison, the parental mouse MAb1H12 was used. For flow cytometry, the adherent cells in culture werewashed with PBS, detached by treatment with trypsin (0.25%) for 1 minand hitting culture dish for full detachment. Trypsin was quenched byadding into the tissue flask the complete medium followed by washing thecells with PBS. During the washing steps, the cells were collected bycentrifugation at 200 g for 5 min. The antibody was diluted for totalconcentration in PBS containing 0.02% bovine serum albumin (BSA). Cellstaining was performed using 200 μL of cell suspension comprising 10⁵cells for 20 min at room temperature. The cell-bound antibodies weredetected with APC-conjugated donkey anti-human or anti-mouse,respectively, IgG (H+L) F(ab′)₂ fragments (Jackson ImmunoResearch).After two washing steps with PBS/0.02% BSA, the cells were resuspendedin 200 μL and kept on ice before analysis on Accuri C6 flow cytometer(BD Biosciences). The results shown in FIG. 9 demonstrated strongbinding of the chimeric antibody to the MDA-MB-231 cells.

Example 11: Affinity Determination of Chimeric Monoclonal Antibodych1H12

Affinity determination of anti-Axl chimeric (mouse variable/humanconstant IgG1) antibody ch1H12 was performed at 25° C. by surfaceplasmon resonance measurements using Biacore 3000 instrument (GEHealthcare). As a solid antigen-coated surface, the sensor chip CM5 withimmobilized rhAxl-Fc chimera (R&D Systems, Cat. no. 154-AL) at density190 RU was used.

For the kinetics measurements, different concentrations of anti-Axlchimeric MAb ch1H12 (from 1.3 to 666.7 nM) in HBS-EP buffer (Biacore,Cat. no. BR-1001-88) were injected at flow rate of 30 μL/min with 3 mininjection time followed by 5 min dissociation (buffer alone). After eachcycle, the surface was regenerated by 30 sec injection of a regenerationsolution (10 mM HCl, 1 M NaCl) at flow rate 50 μL/min.

The mass transfer control experiments demonstrated absence ofsignificant mass transfer limitations for MAb ch1H12. The kineticassociation (on-rate, k_(on)) and dissociation (off-rate, k_(off)) rateswere calculated using BIAevaluation software and 1:1 Langmuir bindingmodel. The equilibrium dissociation constant (K_(D)) was calculated asthe k_(off)/k_(on) ratio. The half-life (t_(1/2)) of the formedantibody-antigen complexes was calculated as the In2/k_(off) ratio.

As shown in FIG. 10, the chimeric MAb ch1H12 demonstrated very highaffinity (K_(D)=1.10×10⁻¹¹ M) mainly due to a very slow dissociationrate (k_(off)=2.99×10⁻⁶ 1/s) which resulted in 64.4 hr half-life of thech1H12/Axl complex. The found affinity value was superior in comparisonwith the parental murine antibody 1H12 (4.5-fold lower K_(D)), which mayindicate better orientation of the V_(H) and V_(L) domains when mountedon a human constant domain scaffold.

Example 12: Mouse Monoclonal Antibody 1H12 Cross-Reacts with Axl fromNon-Human Primates

The recombinant Axl-Fc chimeric proteins comprising extracellularportions of Axl receptor from cynomolgus and rhesus monkeys (cyno-Axland rhe-Axl, respectively) were generated by transient expression in CHOcells. The recombinant cyno-Axl and rhe-Axl antigens were immobilized onthe surface of CM5 sensor chip using amine coupling at the surfacedensity of 1,345.0 and 1,515.9 RU, respectively. As a positive control,hu-Axl-Fc chimera produced under the same conditions was immobilized atthe same chip at density of 1,234.9 RU.

The binding experiments were performed using Biacore 3000 instrument (GEHealthcare) at 25° C. The Biacore runs were performed in an automaticmode using Binding Analysis wizard.

The sample containing MAb 1H12 at concentration 10 μg/mL in HBS-EPbuffer (GE Healthcare) was injected over the surfaces with immobilizedantigens at flow rate of 30 μL/min for 3 min (association) followed by 5min dissociation.

The results shown in FIG. 11 demonstrate strong and specific binding ofMAb 1H12 to all Axl variants on human origin and from cynomolgus andrhesus monkeys.

Example 13: Killing of Tumor Cells Using Chimeric Monoclonal Antibodych1H12 Coupled to Saporin

For generation of immunotoxin, the chimeric MAb ch1H12 wasnon-covalently coupled to a plant toxin Saporin using FabFc-ZAP humanconjugate (4.5 nM final concentration) (Advanced Targeting Systems, Cat.no. IT-65). The effect of ch1H12-Saporin internalization on tumour cellviability was tested using Axl-positive tumour cell line MDA-MB-231(human triple negative breast carcinoma). Eight hundred cells wereseeded per well in 96-well plates in DMEM/F-12 media supplied with 10%FBS, L-glutamine (4 mM), streptomycin (5 μg/ml) and penicillin (5 U/ml)and allowed to attach for 16 hrs. The cells were incubated withdifferent dilutions of immunotoxin ch1H12-Saporin for 72 hrs. Theviability of the cells was determined by performing an XTT/PMS assayusing a CLARIOstar® microplate reader (BMG LABTECH).

The results shown in FIG. 12 demonstrate good internalization and strongcell killing potency of ch1H12-based immunotoxin with EC₅₀ value(effective concentration leading to killing of 50% cells) in picomolarrange.

Example 14: Antibody 1H12 Induces Axl Downstream Signaling

The experiments were performed using human cervical cancer derived cellline HeLa (ATCC® CCL-2™). The cells were grown in T175 flasks to 80%confluency in MEM culture medium (Sigma) supplemented with 10% FBS,penicillin-streptomycin and L-glutamine. The cells were washed with PBSand detached by treatment with 0.25% Trypsin/EDTA (Sigma) followed bycentrifugation and resuspension in fresh medium (MEM/0.5% FBS). Thecells were seeded in Petri dishes (3×10⁶ cells per dish) in MEM mediumsupplemented with 10% FBS. After 7 hrs incubation at 37° C., the cellswere washed with PBS and kept in starvation medium (MEM/0.5% FBS)supplemented with 500 ng/ml of Axl-Fc (R&D Systems) to depleteendogenous Gas6. After 24 hrs incubation, the culture medium wasaspirated and fresh MEM/0.5% FBS medium comprising either anti-Axlantibody 1H12 alone at concentration 7.5 μg/mL or 1H12 premixed withbiotin-SP-conjugated AffiniPure goat anti-mouse IgG (H+L) #2.22 (abcrosslink mixture) was added. After 10-30 min incubation at 37° C., thecells were collected by centrifugation and resuspended in NP40-lysisbuffer followed by 30 min incubation on ice. The cell lysates werecleared by centrifugation (12,000 rpm, 4° C., 5 min) and the proteinconcentrations were determined using BCA protein assay. The cell lysatesamples comprising 35 μg of total protein were denatured in the presenceof the reducing agent (Life Technologies) and loaded into the wells ofNuPAGE 10% Bis-Tris polyacrylamide (PAA) gel, 1.0 mm×12 well(Invitrogen). The electrophoresis was performed using Bis-Tris SDSrunning buffer under the recommended conditions (Life Technologies) andthe proteins were transfer on PVDF membrane, as described for 2 gels ina manual for XCell II™ Blot Module (Invitrogen) using the transferbuffer with 20% methanol. The membrane was incubated in 10 mL ofblocking buffer, TBS/0.1% Tween20 (TBST) with 5% skimmed milk, for 1 hrat room temperature followed by overnight incubation in 5 mL ofincubation buffer (TBST with 3% skimmed milk) containing 1:1000 dilutionof anti-phospho-Akt (Ser⁴⁷³) antibody (Cell Signaling) at 4° C. Themembrane was washed three times for 5 min each with 10 mL of TBSTfollowed by 1 hr incubation with goat anti-rabbit HRP-conjugatedsecondary antibody with gentle rolling at room temperature. Afterwards,the membrane was washed three times for 5 min in 10 mL of TBST and twicewith 10 mL of TBS buffer. The membrane was incubated with 1 mL ECLsubstrate for 1 min at room temperature. Excess substrate solution wasaspirated and the blot was visualised using a ChemiDoc™ XRS+ imager (BioRad) and Image lab software. As loading control, detection usinganti-mouse actin antibody (1:10,000; Sigma) was used under the sameconditions. The anti-phospho-Akt does not distinguish between AKT1,AKT2, and AKT3, hence the total level of ‘phospho-Akt’ is shown in theblot. Detection with anti-GAPDH antibody (Millipore) was used as loadingcontrol.

The results shown in FIG. 13 demonstrated that anti-Axl antibody 1H12cross-linked with the secondary anti-mouse antibody induced strong Axlsignalling in HeLa cells that used downstream phosphorylation of Akt onSer⁴⁷³ as the readout. The effect proved to be dose-dependent, higheramounts of cross-linked 1H12 caused stronger receptor signalling (FIG.14). Furthermore, the data shown in FIG. 15 demonstrate that 1H12antibody can cause Axl receptor activation and downstream signallingalone without crosslinking with secondary antibody. The results indicatethat 1H12 antibody possesses strong agonistic activity.

Example 15: Mouse Monoclonal Antibody 1H12 Competes for Axl Binding withCommercial Antibody MAB154

The competitive binding study was performed using Biacore 3000instrument (GE Healthcare) and Binding Analysis wizard with severalcycles of two samples injection. As a first sample, a saturatingconcentration of MAb 1H12 (1.8 μM or 270 μg/mL) was injected over thesurface of the CM5 sensor chip coated with rhAxl-Fc (using aminecoupling) for 3 min at flow rate of 30 μL/min followed by 2.5 minstabilization (HBS-EP buffer alone) before the injection of the secondsample. The following second samples were used: recombinant mouse (rm)Gas6 (R&D Systems, Cat. no. 986-GS/CF) and a commercial anti-Axlmonoclonal antibody MAB154 (mouse IgG1, Clone #108724; R&D Systems, Cat.No. MAB154); both at concentration 25 μg/mL. As a control, MAb 1H12 wasused as a second sample under the same conditions (25 μg/mL). The secondsample was injected for 3 min, followed by 2.5 min stabilization (bufferalone) and regeneration of the surface by 30 sec injection of aregeneration solution (10 mM HCl, 1 M NaCl) at flow rate 50 μL/min.

The results shown in FIG. 16 demonstrated that the MAb 1H12 inhibitedbinding of MAB154 to Axl and did not compete with mouse Gas6.

Example 16: Comparison of Axl Detection Using 1H12 and CommercialAntibodies

Immunohistochemistry and western blot analysis were performed fordetection of Axl, using MAb 1H12.

On FFPE sections from cell pellets prepared using either Axl+ parentalMDA-MB-231 cells or Axl—MDA-MB-231shAxl2 cells were stained using theMAb 1H12, polyclonal AF154 and monoclonal MAB154 (FIG. 17A). TheMDA-MB-231 shAxl2 cell line has Axl expression knocked down using aretroviral construct expressing an Axl-targeting shRNA; this gives amixed population, where ˜10% of cells remain Axl+.

The best staining of Axl+ cells with MAb 1H12 was achieved with aconcentration of 1 μg/ml (high-score positive staining of cell membranesand weak or no cytoplasmic staining), while the Axl− cells showedpredominantly negative staining with some expression in scattered singlecells. The presence of isolated Axl-expressing cells was consistent withthe observed purity of the MDA-MB-231shAxl2, since—flow cytometryindicated that approximately 90% of the cells carried the retroviralshRNA construct. Comparative staining using AF154 at dilution 1:6400(0.03125 μg/ml03125 μg/mL) and demonstrated somewhat strong membranestaining. However, strong staining was also observed in the Axl− cellsin the scattered population with some weaker expression in most cells.

Staining with MAB154 demonstrated weaker performance than MAb 1H12 onAxl+ cells at similar concentration. However, fewer cells in the Axl−population were weakly stained compared to both MAb 1H12 and AF154. Thisindicates that 1H12 gives improved results as compared to AF154 andMAB154 on IHC.

Similar comparisons were done by Western blot analysis of Axl+ and Axl−cell lysates using the MAb 1H12, AF154 and MAB154 (FIG. 17B). All threeantibodies were used at concentration of 1 μg/ml for the purpose ofrecommendation and visibility. All demonstrated a protein band of Axl at140 kDa in the Axl+ cell lysate. However, this band was nearlyundetectable in Axl− lysates with AF154, although some weak backgroundstaining was detected, which indicates its reaction against otherprotein at low level as noted in previous study Ahmed et al., 2015. Theblot with MAb 1H12 was consistently stronger than that seen with MAB154.From these results we concluded that MAb 1H12 performs significantlybetter than AF154 and MAB154 in western blot.

Sequences

[VH domain (nt)] SEQ ID NO. 1GAGGTGAAGCTGGTGGAATCTGGGGGAGACTTAGTGAAGCCTGGAGGGTCCCTGAAACTCTCCTGTGCAGCCTCTGGATTCACTTTCAGTAGCTATGGCATGTCTTGGGTTCGCCAGACTCCAGACAAGAGGCTGGAGTGGGTCGCAACCATTAGTAGTGGTGGTAGTTACACCTACTATCCAGACAGTGTGAAGGGGCGATTCACCATCTCCAGAGACAATGCCAAGAACACCCTGTACCTGCAAATGAGCAGTCTGAAGTCTGAGGACACAGCCATGTATTACTGTGCAAGACATCCCATCTACTATACTTACGACGATACTATGGACTACTGGGGTCAAGGAACCTCAGTCACCGTCTCCTCAGCCAAAACGACACCC [VL domain (nt)] SEQ ID NO. 2GACATTGTGCTGACCCAATCTCCAGCAATCATGGCTGCATCTCCAGGGGAGAAGGTCACCATGACCTGCAGTGCCAGCTCAAGTGTAAGTTCTGGTAACTTTCACTGGTACCAGCAGAAGCCAGGCACTTCTCCCAAACTCTGGATTTATAGGACATCCAACCTGGCTTCTGGAGTCCCCGCTCGCTTCAGTGGCAGTGGGTCTGGGACCTCTTACTCTCTTACAATCAGCAGCATGGAGGCCGAAGATGCTGCCACTTATTACTGCCAGCAGTGGAGTGGTTACCCGTGGACGTTCGGTGGAGGCACCAAGCTGGAAATCAAACGGGCTGATGCTGCACCAACTGTATC C [VH domain (aa)]SEQ ID NO. 3 EVKLVESGGDLVKPGGSLKLSCAASGFTFSSYGMSVVVRQTPDKRLEWVATISSGGSYTYYPDSVKGRFTISRDNAKNTLYLQMSSLKSEDTAMYYCARHPIYYTYDDTMDYWGQGTSVTVSS [VL domain (aa)] SEQ ID NO. 4 DIVLTQSPAIMAASPGEKVTMTCSASSSVSSGNFHVVYQQKPGTSPKLWIYRTSNLASGVPARFSGSGSGTSYSLTISSMEAEDAATYYCQQWSGYPWTF GGGTKLEIK[Heavy CDR1] SEQ ID NO .5 GFTFSSYGMS [Heavy CDR2] SEQ ID NO. 6TISSGGSYTYYPDSVKGRFTISRDNA [Heavy CDR3] SEQ ID NO. 7 HPIYYTYDDTMDY[Light CDR1] SEQ ID NO. 8 SASSSVSSGNFH [Light CDR2] SEQ ID NO. 9 RTSNLAS[Light CDR3] SEQ ID NO. 10 QQWSGYPWT [Heavy FR1] SEQ ID NO. 11EVKLVESGGDLVKPGGSLKLSCAAS [Heavy FR2] SEQ ID NO. 12 WVRQTPDKRLEWVA[Heavy FR3] SEQ ID NO. 13 KNTLYLQMSSLKSEDTAMYYCAR [Heavy FR4]SEQ ID NO. 14 WGQGTSVTVSS [Light FR1] SEQ ID NO. 15DIVLTQSPAIMAASPGEKVTMTC [Light FR2] SEQ ID NO. 16 WYQQKPGTSPKLWIY[Light FR3] SEQ ID NO. 17 GVPARFSGSGSGTSYSLTISSMEAEDAATYYC [Light FR4]SEQ ID NO. 18 FGGGTKLEIK [Human Axl] SEQ ID NO. 19 MAWRCPRMGRVPLAWCLALCGWACMAPRGTQAEESPFVGNPGNITGARGLTGTLRCQLQVQGEPPEVHWLRDGQILELADSTQTQVPLGEDEQDDWIVVSQLRITSLQLSDTGQYQCLVFLGHQTFVSQPGYVGLEGLPYFLEEPEDRTVAANTPFNLSCQAQGPPEPVDLLWLQDAVPLATAPGHGPQRSLHVPGLNKTSSFSCEAHNAKGVTTSRTATITVLPQQPRNLHLVSRQPTELEVAWTPGLSGIYPLTHCTLQAVLSDDGMGIQAGEPDPPEEPLTSQASVPPHQLRLGSLHPHTPYHIRVACTSSQGPSSWTHWLPVETPEGVPLGPPENISATRNGSQAFVHWQEPRAPLQGTLLGYRLAYQGQDTPEVLMDIGLRQEVTLELQGDGSVSNLTVCVAAYTAAGDGPWSLPVPLEAWRPGQAQPVHQLVKEPSTPAFSWPWWYVLLGAVVAAACVLILALFLVHRRKKETRYGEVFEPTVERGELVVRYRVRKSYSRRTTEATLNSLGISEELKEKLRDVMVDRHKVALGKTLGEGEFGAVMEGQLNQDDSILKVAVKTMKIAICTRSELEDFLSEAVCMKEFDHPNVMRLIGVCFQGSERESFPAPVVILPFMKHGDLHSFLLYSRLGDQPVYLPTQMLVKFMADIASGMEYLSTKRFIHRDLAARNCMLNENMSVCVADFGLSKKIYNGDYYROGRIAKMPVKWIAIESLADRVYTSKSDVWSFGVTMWEIATRGQTPYPGVENSEIYDYLRRGNRLKQPADCLDGLYALMSRCWELNPQDRPSFTELREDLENTLKALPPAQEPDEILYVNMDEGGGYPEPPGAAGGADPPTQPDPKDSCSCLTAAEVHPAGRYVLCPSTTPSPAQPADRGSPAAPGQEDGA [Murine Axl] SEQ ID NO. 20MGRVPLAWWLALCCWGCAAHKDTQTEAGSPFVGNPGNITGARGLTGTLRCELQVQGEPPEVVWLRDGQILELADNTQTQVPLGEDWQDEWKVVSQLRISALQLSDAGEYQCMVHLEGRTFVSQPGFVGLEGLPYFLEEPEDKAVPANTPFNLSCQAQGPPEPVTLLWLQDAVPLAPVTGHSSQHSLQTPGLNKTSSFSCEAHNAKGVTTSRTATITVLPQRPHHLHVVSRQPTELEVAWTPGLSGIYPLTHCNLQAVLSDDGVGIWLGKSDPPEDPLTLQVSVPPHQLRLEKLLPHTPYHIRISCSSSQGPSPWTHWLPVETTEGVPLGPPENVSAMRNGSQVLVRWQEPRVPLQGTLLGYRLAYRGQDTPEVLMDIGLTREVTLELRGDRPVANLTVSVTAYTSAGDGPWSLPVPLEPWRPGQGQPLHHLVSEPPPRAFSWPWWYVLLGALVAAACVLILALFLVHRRKKETRYGEVFEPTVERGELVVRYRVRKSYSRRTTEATLNSLGISEELKEKLRDVMVDRHKVALGKTLGEGEFGAVMEGQLNQDDSILKVAVKTMKIAICTRSELEDFLSEAVCMKEFDHPNVMRLIGVCFQGSDREGFPEPVVILPFMKHGDLHSFLLYSRLGDQPVFLPTQMLVKFMADIASGMEYLSTKRFIHRDLAARNCMLNENMSVCVADFGLSKKIYNGDYYROGRIAKMPVKWIAIESLADRVYTSKSDVWSFGVTMWEIATRGQTPYPGVENSEIYDYLRQGNRLKQPVDCLDGLYALMSRCWELNPRDRPSFAELREDLENTLKALPPAQEPDEILYVNMDEGGSHLEPRGAAGGADPPTQPDPKDSCSCLTAADVHSAGRYVLCPSTAPGPTLSADRGCPAPPGQEDGA [Human Tyro3] SEQ ID NO. 21MALRRSMGRPGLPPLPLPPPPRLGLLLAALASLLLPESAAAGLKLMGAPVKLTVSQGQPVKLNCSVEGMEEPDIQWVKDGAVVQNLDQLYIPVSEQHWIGFLSLKSVERSDAGRYWCQVEDGGETEISQPVWLTVEGVPFFTVEPKDLAVPPNAPFQLSCEAVGPPEPVTIVWWRGTTKIGGPAPSPSVLNVTGVTQSTMFSCEAHNLKGLASSRTATVHLQALPAAPFNITVTKLSSSNASVAWMPGADGRALLQSCTVQVTQAPGGWEVLAVVVPVPPFTCLLRDLVPATNYSLRVRCANALGPSPYADVVVPFQTKGLAPASAPQNLHAIRTDSGLILEWEEVIPEAPLEGPLGPYKLSVVVQDNGTQDELTVEGTRANLTGWDPQKDLIVRVCVSNAVGCGPWSQPLVVSSHDRAGQQGPPHSRTSWVPVVLGVLTALVTAAALALILLRKRRKETRFGQAFDSVMARGEPAVHFRAARSFNRERPERIEATLDSLGISDELKEKLEDVLIPEQQFTLGRMLGKGEFGSVREAQLKQEDGSFVKVAVKMLKADIIASSDIEEFLREAACMKEFDHPHVAKLVGVSLRSRAKGRLPIPMVILPFMKHGDLHAFLLASRIGENPFNLPLQTLIRFMVDIACGMEYLSSRNFIHRDLAARNCMLAEDMTVCVADFGLSRKIYSGDYYRQGCASKLPVKWLALESLADNLYTVQSDVWAFGVTMWEIMTRGQTPYAGIENAEIYNYLIGGNRLKQPPECMEDVYDLMYQCWSADPKQRPSFTCLRMELENILGQLSVLSASQDPLYINIERAEEPTAGGSLELPGRDQPYSGAGDGSGMGAVGGTPSDCRYILTPGGLAEQPGQAEHQPESPLNETQRLLLLQQGLLPHSSC [Human MeR] SEQ ID NO. 22MKINNEEIVSDPIYIEVQGLPHFTKQPESMNVTRNTAFNLTCQAVGPPEPVNIFWVQNSSRVNEQPEKSPSVLTVPGLTEMAVFSCEAHNDKGLTVSKGVQINIKAIPSPPTEVSIRNSTAHSILISWVPGFDGYSPFRNCSIQVKEADPLSNGSVMIFNTSALPHLYQIKQLQALANYSIGVSCMNEIGWSAVSPWILASTTEGAPSVAPLNVTVFLNESSDNVDIRWMKPPTKQQDGELVGYRISHVWQSAGISKELLEEVGQNGSRARISVQVHNATCTVRIAAVTKGGVGPFSDPVKIFIPAHGWVDYAPSSTPAPGNADPVLIIFGCFCGFILIGLVLYISLAIRKRVQETKFGNAFTEEDSELVVNYIAKKSFCRRAIELTLHSLGVSEELQNKLEDVVIDRNLLILGKILGEGEFGSVMEGNLKQEDGTSLKVAVKTMKLDNSSQREIEEFLSEAACMKDFSHPNVIRLLGVCIEMSSQGIPKPMVILPFMKYGDLHTYLLYSRLETGPKHIPLQTLLKFMVDIALGMEYLSNRNFLHRDLAARNCMLRDDMTVCVADFGLSKKIYSGDYYRQGRIAKMPVKWIAIESLADRVYTSKSDVWAFGVTMWEIATRGMTPYPGVQNHEMYDYLLHGHRLKQPEDCLDELYEIMYSCWRTDPLDRPTFSVLRLQLEKLLESLPDVRNQADVIYVNTQLLESSEGLAQGSTLAPLDLNIDPDSIIASCTPRAAISVVTAEVHDSKPHEGRYILNGGSEEWEDLTSAPSAAVTAEKNSVLPGERLVRNGVSWSHSSMLPLGSSLPDELLFADDSSEGSEVLM

1. An antibody that binds Axl and which comprises: an antibody VH domainselected from (a) the 1H12 VH domain (SEQ ID NO.3); (b) a VH domaincomprising a VH CDR3 domain with the amino acid sequence of SEQ ID NO.7;and (c) a VH domain comprising a VH CDR3 domain with the amino acidsequence of SEQ ID NO.7 and one or more VH CDR's with an amino acidsequence selected from SEQ ID NO.6 and SEQ ID NO.5; and/or an antibodyVL domain selected from (a) the 1H12 VL domain (SEQ ID NO. 4); and (b) aVL domain comprising one or more VL CDR's with an amino acid sequenceselected from SEQ ID NO.8, SEQ ID NO.9 and SEQ ID NO.10.
 2. The antibodyaccording to claim 1 comprising an antibody VH domain comprising the VHCDR's with the amino acid sequences of SEQ ID NO.5, SEQ ID NO.6 and SEQID NO.7, wherein the which antibody competes for binding to Axl with anAxl binding domain of an antibody comprising the 1H12 VH domain (SEQ IDNO. 3) and the 1H12 VL domain (SEQ ID NO. 4).
 3. The antibody accordingto claim 1 comprising the 1H12 VH domain (SEQ ID NO. 3).
 4. The antibodyaccording to claim 3 comprising the 1H12 VL domain (SEQ ID NO. 4)
 5. Avariant of an antibody according to claim 1, wherein the variantcomprises one or more amino acid sequence alterations in one or moreframework regions and/or one or more CDRs.
 6. The antibody according toclaim 1 that binds Axl with affinity equal to or better than theaffinity of an Axl antigen-binding site formed by the 1H12 VH domain(SEQ ID NO. 3) and the 1H12 VL domain (SEQ ID NO. 4), wherein theaffinity of the antibody and the affinity of the antigen-binding siteare determined under the same conditions.
 7. The antibody according toclaim 1, wherein the antibody is a whole antibody or an antigen-bindingfragment selected from a single domain antibody, Fv, scFv, dsFv, Fd,Fab, F(ab′)₂, minibody, diabody, single-chain diabody, tandem scFv,TandAb, bi-body, tri-body, kappa(lambda)-body, BiTE, DVD-Ig, SIP, SMIP,and DART. 8-11. (canceled)
 12. The antibody according to claim 1,wherein the antibody binds to Axl with a K_(D) no greater than 5×10⁻¹¹M.
 13. (canceled)
 14. The antibody according to claim 1, wherein theantibody binds to Axl with a k_(off) no greater than 2×10⁻⁵ s⁻¹. 15.(canceled)
 16. The antibody according to claim 1 wherein the Axl ishuman Axl.
 17. The antibody according to claim 1 which specificallybinds primate Axl.
 18. The antibody according to claim 1 which: (i)binds murine Axl with a K_(D) greater than 10⁻³ M; (ii) binds human Merwith a K_(D) greater than 10⁻³ M; and/or (iii) binds human Tyro3 with aK_(D) greater than 10⁻³ M.
 19. The antibody according to claim 1 whereinthe antibody is an Axl agonist. 20-21. (canceled)
 22. The antibodyaccording to claim 1 wherein the antibody is a humanised antibody. 23.The antibody according to claim 1 wherein the antibody binds: (i) thesame epitope as the 1H12 antibody, or (ii) an epitope which overlapswith the epitope bound by the 1H12 antibody.
 24. The antibody accordingto claim 1 wherein the antibody is internalised following binding to Axlpresent on a cell surface.
 25. The antibody according to claim 1 whereinthe antibody is conjugated to a detectable label, enzyme, or toxin via apeptidyl bond or linker. 26-27. (canceled)
 28. An isolated nucleic acidwhich comprises a nucleotide sequence encoding the antibody or antibodyVH or VL domain of the antibody according to claim
 1. 29. A host celltransformed with the nucleic acid according to claim
 28. 30. A method ofproducing an antibody or antibody VH or VL domain, the method comprisingculturing host cells according to claim 29 under conditions forproduction of said antibody or antibody VH or VL domain.
 31. The methodaccording to claim 30 further comprising isolating and/or purifying saidantibody or antibody VH or VL variable domain.
 32. The method accordingto claim 30 further comprising formulating the antibody or antibody VHor VL variable domain into a composition including at least oneadditional component.
 33. A method of obtaining an antibody that bindsAxl, comprising: providing by way of addition, deletion, substitution orinsertion of one or more amino acids in the amino acid sequence of the1H12 VH domain (SEQ ID NO. 3) one or more VH domains each of which is anamino acid sequence variant of the 1H12 VH domain, and combining one ormore VH domain amino acid sequence variants thus provided with one ormore VL domains to provide one or more VH/VL combinations; and/orproviding by way of addition, deletion, substitution or insertion of oneor more amino acids in the amino acid sequence of the 1H12 VL domain(SEQ ID NO. 4) a VL domain which is an amino acid sequence variant ofthe 1H12 VL domain, and combining one or more VL domain amino acidsequence variants thus provided with one or more VH domains to provideone or more VH/VL domain combinations; and testing the VH domain aminoacid sequence variants or VH/VL combination or combinations to identifyan antibody that binds Axl.
 34. A method of obtaining an antibody thatbinds Axl, comprising: (a) providing starting nucleic acids encoding oneor more VH domains which either comprise a CDR3 to be replaced or lack aCDR3 encoding region, and combining said starting nucleic acid with adonor nucleic acid encoding the VH CDR3 amino acid sequence of SEQ IDNO.7 such that said donor nucleic acid is inserted into the CDR3 regionin the starting nucleic acid, so as to provide product nucleic acidsencoding VH domains; or providing starting nucleic acids encoding one ormore VL domains which either comprise a CDR3 to be replaced or lack aCDR3 encoding region, and combining said starting nucleic acid with adonor nucleic acid encoding the VL CDR3 amino acid sequence of SEQ IDNO.10 such that said donor nucleic acid is inserted into the CDR3 regionin the starting nucleic acid, so as to provide product nucleic acidsencoding VL domains; (b) expressing the nucleic acids of said productnucleic acids encoding VH domains and combining the VH domains thusproduced with one or more VL domains to provide VH/VL combinations,and/or expressing the nucleic acids of said product nucleic acidsencoding VL domains and combining the VL domains thus produced with oneor more VH domains to provide VH/VL combinations; (c) selecting anantibody comprising a VH domain or a VH/VL combination that binds Axl;and (d) recovering said antibody that binds Axl and/or nucleic acidencoding the antibody that binds Axl.
 35. (canceled)
 36. The methodaccording to claim 34 wherein the antibody is a scFv antibody moleculeor Fab antibody molecule. 37-40. (canceled)
 41. A method comprising (a)binding an antibody that binds Axl according to claim 1 to Axl or afragment of Axl; and (b) determining the amount of binding of antibodyto Axl or a fragment of Axl. 42-45. (canceled)
 46. A compositioncomprising an antibody according to claim 1, or an immunoconjugatethereof, and a pharmaceutically acceptable excipient.
 47. Thecomposition according to claim 46 further comprising an immunecheckpoint modulator (ICM). 48-53. (canceled)
 54. A method of treatmentof a disease or disorder characterised by overexpression of Axl, themethod comprising administering an antibody according to claim 1 to apatient with the disease or disorder or is at risk of developing thedisease or disorder.
 55. The method according to claim 54, wherein theantibody is coupled to a cytotoxic agent.
 56. (canceled)
 57. A method ofdiagnosis of a disease or disorder characterised by overexpression ofAxl, the method comprising administering an antibody according to claim1 and one or more reagents that allow determination of the binding ofsaid antibody to metastatic cancer cells, to a patient with the diseaseor disorder or is at risk of developing the disease or disorder.
 58. Adiagnostic kit comprising an antibody according to claim 1 and one ormore reagents that allow determination of the binding of said antibodyto metastatic cancer cells. 59-60. (canceled)